CN103913490A - Electrochemistry Analysis Method, Electrochemistry Analysis Device And Test Kit - Google Patents
Electrochemistry Analysis Method, Electrochemistry Analysis Device And Test Kit Download PDFInfo
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- CN103913490A CN103913490A CN201310655479.8A CN201310655479A CN103913490A CN 103913490 A CN103913490 A CN 103913490A CN 201310655479 A CN201310655479 A CN 201310655479A CN 103913490 A CN103913490 A CN 103913490A
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- 238000004458 analytical method Methods 0.000 title claims abstract description 23
- 230000005518 electrochemistry Effects 0.000 title abstract 6
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims abstract description 108
- 229910052793 cadmium Inorganic materials 0.000 claims abstract description 106
- 239000002253 acid Substances 0.000 claims abstract description 16
- 238000000605 extraction Methods 0.000 claims abstract description 10
- XNGIFLGASWRNHJ-UHFFFAOYSA-N phthalic acid Chemical compound OC(=O)C1=CC=CC=C1C(O)=O XNGIFLGASWRNHJ-UHFFFAOYSA-N 0.000 claims description 44
- 238000000034 method Methods 0.000 claims description 38
- 239000010949 copper Substances 0.000 claims description 36
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 35
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- 239000012472 biological sample Substances 0.000 claims description 30
- 238000000840 electrochemical analysis Methods 0.000 claims description 21
- 238000004070 electrodeposition Methods 0.000 claims description 20
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 claims description 16
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- 239000001257 hydrogen Substances 0.000 claims description 10
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- 150000001880 copper compounds Chemical class 0.000 claims description 6
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- 238000012423 maintenance Methods 0.000 description 13
- 241000209094 Oryza Species 0.000 description 12
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- 238000003756 stirring Methods 0.000 description 4
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- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
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- Sampling And Sample Adjustment (AREA)
Abstract
The present invention provides an electrochemistry analysis method, an electrochemistry analysis device and a test kit which can detect and quantify cadmium contained in a sample coming from a biont at high sensitivity and precision. The electrochemistry analysis method is to analyze the cadmium contained in the sample coming from the biont in an electrochemistry manner by using a counter electrode (3) and an action electrode (5), and possesses an extraction step, a step of adding acid which possesses oxidability to the sample coming from the biont and does not form a complex with the cadmium, and a step of extracting the cadmium from the above sample coming from the biont.
Description
Technical field
The present invention relates to detect with electrochemical means the method, device and the reagent set that derive from the cadmium containing in biological sample.
Background technology
Known cadmium is toxic to human body, if cadmium is put aside in vivo, renal function etc. can sustain damage.Therefore, set standard for the amount of the cadmium containing in the food including rice, in food hygiene law, in brown rice, be defined as below 1ppm, while containing cadmium more than standard value, can not peddle, be all incinerated.In addition, according to the notice in the grain Room, the rice that detects cadmium more than 0.4ppm in brown rice is by all as industrial use.
In the past, as analyzing the method for cadmium, known had as the atomic absorption analysis method of the analytic approach of statutory regulation, ICP luminescence analysis, ICP mass analysis etc.But, the huge costliness of device of carrying out these analyses, and its operation is also complicated.
On the other hand, although also in the trial (patent documentation 1) of carrying out analyzing with electrochemical means cadmium, in the time will analyzing the cadmium containing in food, the organism containing in this food has hindered the realization of high-precision analysis as disturbing factor.
Patent documentation 1: TOHKEMY 2005-49275 communique
Summary of the invention
Therefore, the object of the present invention is to provide a kind of can high sensitive and detect and quantitatively derive from accurately electrochemical analysis method, device and the reagent set of the cadmium containing in biological sample.
; electrochemical analysis method of the present invention; it is use derives from the cadmium containing in biological sample with electrochemical means analysis method to electrode and active electrode; possesses abstraction process; it adds to deriving from biological sample the acid that has oxidisability and do not form complex compound with cadmium, extracts cadmium from above-mentioned deriving from biological sample.
By using the acid that there is like this oxidisability and do not form complex compound with cadmium, always biogenic sample extraction cadmium, be contained in thereby can decompose well the organism that derives from biological sample, and because this acid and cadmium do not form complex compound, therefore can carry out accurately the detection of cadmium, the mensuration of its concentration.
As the above-mentioned acid that there is oxidisability and do not form complex compound with cadmium, preferably use perchloric acid.At this, in ICP luminescence analysis, ICP mass analysis, although hydrochloric acid is used to derive from the pre-service of biological sample, if use hydrochloric acid to carry out the extraction of cadmium, current peak when cadmium is from active electrode stripping diminishes, and is difficult to carry out high-precision analysis.This is because hydrochloric acid, sulfuric acid and cadmium form complex compound.
Preferably, the pH value of the extract obtaining is adjusted into 3～7.More preferably pH value is 3～6.If pH value does not reach 3, current peak when cadmium is from active electrode stripping diminishes, and is difficult to carry out high-precision analysis.On the other hand, if pH value exceedes 7, cadmium precipitates.
Preferably, the pH value of said extracted liquid is adjusted into at 3～7 o'clock, uses the buffering agent being formed by organic acid and/or its salt.Organic acid carboxyl has chelating effect, and this carboxyl parcel becomes the metals such as the lead, selenium, chromium, boron of disturbing factor while analyzing cadmium, thereby is speculated as the interference having prevented cadmium.As above-mentioned organic acid, preferably carboxyl possesses 1 or 2 in a molecule, for example, can enumerate phthalic acid, acetic acid etc.In addition, use in the situation of phthalic acid, preferably pH value is adjusted into 4 left and right, use in the situation of acetic acid, preferably pH value is adjusted into 5 left and right.
Deriving from the extract of biological sample, conventionally form the complex of cadmium and copper, in this situation, in electrochemical analysis, the current peak of the complex that derives from cadmium and copper detected.Therefore,, in order to make measurement result do not derived from the impact of the amount of the copper in biological sample, can be in advance add copper deriving from biological sample.As the addition of copper now, for example, can add and (for example not reach pre-determined reference value, as expecting the maximum amount of copper in the biological sample of deriving from of target) the copper of component, also can add copper with the concentration of 3～10 times of left and right of the mensuration concentration range of cadmium (greatly superfluous).Add when copper, can use the copper compound of the electrolyte etc. of copper.
Electrochemical analysis method of the present invention, preferably, possess electrode clean operation, under the state contacting with solution (the said extracted liquid phase after the acid of this solution and the composition of buffering agent and pH value are adjusted with pH value is same) at above-mentioned active electrode, apply positive voltage at above-mentioned active electrode.By carrying out this electrode clean operation, can remove in advance the organism, the heavy metal that adhere to active electrode, therefore can carry out high-precision analysis.
As above-mentioned active electrode, there is no particular limitation, preferably uses carbon electrode, wherein, more preferably uses conductive diamond electrode.As this conductive diamond electrode, for example, can enumerate electrode doped with boron, nitrogen, phosphorus etc. etc., wherein the boron-doped diamond electrode of high concentration boron-doping preferably.Boron-doped diamond electrode has potential window large (oxidizing potential and reduction potential scope are wide), electrode material background current than other is low, highly sensitive to reductant-oxidant, compare with gold, platinum etc., be difficult to occur that owing to being difficult to generate the absorption of physics at electrode surface, therefore having oxygen, hydrogen produce the good character of peak value in addition.In addition, boron-doped diamond electrode has good chemical durability, mechanical robustness, electric conductivity, corrosion resistance etc.Further, boron-doped diamond electrode, due to its hardness, also has the cleaning that is easy to carry out chemistry, physics, is easy to electrode surface to maintain the advantage of clean state.
In addition,, can use for example by platinum, carbon, stainless steel, gold, adamas, SnO electrode for above-mentioned
2at the electrode forming, further, use in the situation of reference electrode, can suitably use known electrode, can use for example silver silver chloride electrode, mercurous chloride electrode, standard hydrogen electrode, palladium hydrogen electrode etc.
In the present invention, in the case of use active electrode for conductive diamond electrode, after above-mentioned electrode clean operation, further, preferably carry out applying negative voltage at above-mentioned conductive diamond electrode, make the hydrogen end-blocking chemical industry order of electrode surface hydrogen end-blocking.By so the processing of hydrogen end-blocking being carried out in the surface of conductive diamond electrode, thereby the sensitivity of electrode surface is improved, can carry out high-precision analysis.
Electrochemical analysis method of the present invention, can implement according to the analytical equipment for example having as following structure.; for derive from the device of the cadmium that biological sample contains with electrochemical means analysis; possess: extraction element, it adds to deriving from biological sample the acid that has oxidisability and do not form complex compound with cadmium, extracts cadmium from above-mentioned deriving from biological sample; PH value adjuster, its pH value by the extract obtaining is adjusted into 3～7; For built-in to electrode and active electrode, hold the unit of said extracted liquid; Bringing device, it makes cadmium or its complex electro-deposition in the voltage of above-mentioned active electrode at above-mentioned active electrode and above-mentioned applying between to electrode, then, applies and makes electro-deposition in the voltage of the cadmium of above-mentioned active electrode or its complex stripping; Pick-up unit, its detection results from above-mentioned active electrode and above-mentioned to the electric current between electrode.So electrochemical analytical equipment is also an aspect of of the present present invention.
In addition, while implementing electrochemical analysis method of the present invention, in order to derive from biological sample and to extract cadmium from this, and adjust the extract obtaining for mensuration, can use and comprise the acid, the buffering agent being formed by organic acid and/or its salt and the reagent set of copper compound that there is oxidisability and do not form complex compound with cadmium.So reagent set is also an aspect of of the present present invention.
In reagent set of the present invention, have oxidisability and with cadmium form acid (A composition), the buffering agent (B composition) being formed by organic acid and/or its salt and the copper compound (C composition) of complex compound can be respectively as independent reagent preparation, also can make A composition and C composition be contained in a kind of reagent or make B composition and C composition is contained in a kind of reagent.In addition, as the formulation of the reagent containing in this reagent set, there is no particular limitation, can be solid-state (Powdered, tablet), can be also liquid.
According to the present invention of formation like this, can decompose well and derive from organism contained in biological sample, and not form and the complex compound of cadmium, therefore can carry out accurately the detection of cadmium, the mensuration of its concentration.
Brief description of the drawings
Fig. 1 is the schematic diagram that represents the formation of the electrochemical determining device of present embodiment.
Fig. 2 is the stereographic map that schematically represents the heavy metal ion determinator of same embodiment.
Fig. 3 is the sectional view that schematically represents the structure of the determination unit of same embodiment.
Fig. 4 is the stereographic map of the stirrer of same embodiment.
Fig. 5 is the vertical view of the stirrer of same embodiment.
Fig. 6 is the front elevation of the stirrer of same embodiment.
Fig. 7 is the right view of the stirrer of same embodiment.
Fig. 8 is the figure that schematically represents the manufacture method of the stirrer of same embodiment.
Fig. 9 is the 1st schematic diagram that represents the concrete structure of the determination unit inside of same embodiment.
Figure 10 is the 2nd schematic diagram that represents the concrete structure of the determination unit inside of same embodiment.
Figure 11 is the volt-ampere characteristic while using perchloric acid to extract cadmium from rice.
Figure 12 is the volt-ampere characteristic while using hydrochloric acid to extract cadmium from rice.
Figure 13 is the schematic diagram that represents the variation that keeps face.
Figure 14 is the schematic diagram that represents the variation that keeps face.
Symbol description:
100 electrochemical determining devices
2 determination units
2P surface of contact
2Q keeps face
Lateral circle surface in 2X
3 pairs of electrodes
4 reference electrodes
5 active electrodes
91 stirrers
911a opposed faces
91b outside circumference
91H insertion through hole
911 bodies
912 blade parts
Embodiment
Below, with reference to the accompanying drawings of electrochemical determining device of the present invention.
The electrochemical determining device 100 of present embodiment is for using the stripping voltammetry of the three electrode modes to electrode, reference electrode and active electrode to analyze the cadmium containing in biological sample that derives from of such as rice etc.
(apparatus structure)
Particularly, electrochemical determining device 100 as shown in Figure 1, possesses the determination unit 2 of receiving fluids sample, contact with fluid sample arrange to electrode 3, reference electrode 4, and active electrode 5, the current potential change portion 6 that the current potential of active electrode 5 is changed, at least a portion of the fluid sample that is contained in determination unit 2 is replaced to mechanism 11 with the liquid of replacing as the acidic buffer of mensuration solution, detection effect electrode 5 and the current detecting part 7 to the electric current between electrode 3, calculate the concentration calculating part 8 of concentration of heavy metal ion according to the current value being detected by current detecting part 7.
In addition, above-mentioned each inscape as shown in Figure 2, is contained in cover C, holds the buffering flow container T1 of above-mentioned acidic buffer and receiving fluids sample, the waste liquid tank T2 of the waste liquid of damping fluid after using etc. front lower being provided with of this cover C.In addition, in the front upper of cover C, power source ON/OFF button is set, measures the operation button group B of start button, correcting button, cleaning button etc. and shows the display part 801 of measurement result (concentration etc.).Further, on the top of cover C, be provided with the Sample introduction portion 21 for fluid sample being injected into said determination unit 2.
First, current potential change portion 6, current detecting part 7, liquid displacement mechanism 11 and concentration calculating part 8 are described.
Current potential change portion 6 and current detecting part 7 are made up of potentiostat PS.This potentiostat PS the current potential that makes active electrode 5 for reference electrode 4 for fixing state under, detection effect electrode 5 and electric current to generation between electrode 3, output to this detection signal the calculation control device 8 of the function with concentration calculating part described later.
This potentiostat PS is with regard to the function about current potential change portion 6, and the current potential that makes active electrode 5 is in heavy metal electro-deposition in the current potential of active electrode 5, and stripping electro-deposition changes between the current potential of the heavy metal of active electrode 5.Particularly, potentiostat PS is with the state of active electrode 5 contact liq samples, the current potential of active electrode 5 is changed to negative potential direction, supply makes the heavy metal electro-deposition of measuring target in the surperficial current potential of active electrode 5, then, the state contacting with the O-phthalic acid buffer as acidic buffer using above-mentioned heavy metal electro-deposition in surperficial active electrode 5, to positive potential direction, supplies with the electric potential scanning of active electrode 5 to make electro-deposition in the current potential of the leaching ability of heavy metal of active electrode 5.
In addition, potentiostat PS is with regard to regard to current sense function, detects by above-mentioned current potential and changes function and by the electric potential scanning of active electrode 5 during to positive potential direction, active electrode 5 and the electric current to generation between electrode 3.
In addition, potentiostat PS, except keeping the function of set potential, also has with fixed speed scanning current potential, according to regular time interval carry out the functions such as step with the current potential of having specified.These functions are not to be equipped on same table apparatus, for example, current potential can be kept function and electric potential scanning function setting to install in other yet.
Liquid displacement mechanism 11, as shown in Figure 1, has the discharge line 12 for the liquid in determination unit 2 being discharged to waste liquid tank T2, and from buffering flow container T1, O-phthalic acid buffer is supplied to the feeding pipe 13 of determination unit 2.
Discharge line 12 has the vent pipe 121 being connected with determination unit 2, and is arranged at this vent pipe 121 for the fluid removal that is contained in determination unit 2 is arrived to outside extraction pump 122.Vent pipe 121 is set to, in the mode at active electrode 5 near surface openings, the bottom wall part 2c of determination unit 2 is connected to (not shown).In addition, the downstream of vent pipe 121 is connected with waste liquid tank T2.In addition, extraction pump 122 is controlled its working time etc. by calculation control device 8 described later.
Feeding pipe 13 has and is connected in the supply pipe 131 of determination unit 2 and is arranged at this supply pipe 131 for the O-phthalic acid buffer that is contained in buffering flow container T1 being supplied to the charge pump 132 of determination unit 2.Supply pipe 131, with to electrode 3 and reference electrode 4 similarly, tilts to insert fixing (not shown) at the side wall portion 2b of determination unit 2 in the mode towards active electrode 5.In addition, the upstream side of supply pipe 131 is connected with buffering flow container T1.In addition, charge pump 132 is controlled its working time etc. by calculation control device 8 described later.
This liquid displacement mechanism 11 is controlled by calculation control device 8, so that the fluid sample that is contained in determination unit 2 is at least being kept to, under the state of the liquid measure that electrode 3 and active electrode 5 are contacted with fluid sample, carry out liquid displacement.Particularly, extraction pump 122 and the charge pump 132 of liquid displacement mechanism 11 are controlled by calculation control device 8, replace the fluid sample that is contained in determination unit 2 is divided into repeatedly with as the mensuration O-phthalic acid buffer of solution.For example, liquid displacement mechanism 11 by fluid sample for example each half and half and O-phthalic acid buffer several times (for example 4 left and right) replace.As method of replacing, after the fluid sample that is contained in determination unit 2 is discharged to half by discharge line 12, the O-phthalic acid buffer by feeding pipe 13 supplies with discharge rate a great deal of.So for example repeatedly for several times.In addition, also can carry out the discharge of fluid sample and the supply of O-phthalic acid buffer simultaneously.
Calculation control device 8 is to obtain the detection signal being detected by potentiostat PS, carries out the device of detection and the concentration determination of heavy metal ion.Particularly, calculation control device 8 is the general and special devices that possess the output units such as CPU, storer, IO channel, display 801, A/D transducer, D/A transducer etc., above-mentioned CPU with and peripheral plane device by the mensuration program cooperative work in the presumptive area storage of above-mentioned storer, thereby carry out mensuration program described later.In addition, calculation control device 8, needn't be integrated in structure, also can be by wired or be wirelessly divided into multiple machines.
Then, determination unit 2 is described, is arranged at the electrode group 3～5 of this determination unit 2 and is arranged at the rabbling mechanism 9 of this determination unit 2.
Determination unit 2, as shown in Figure 3, for form the device of the spatial accommodation 2S of fluid sample in inside, the 2a of wall portion is formed for importing the Sample introduction portion 21 of fluid sample thereon.
In addition, at the side wall portion 2b of determination unit 2, tilt to insert fixing to electrode 3 and reference electrode 4 in the mode towards downside (bottom wall part 2c side).Further, be fixed in the mode of exposing at spatial accommodation 2S at the bottom wall part 2c of determination unit 2 active electrode 5.
Here, with regard to the electrode group 3～5 about present embodiment, be for example platinum electrode to electrode 3, reference electrode 4 is for example silver-silver chloride electrode, active electrode 5 is boron-doped diamond (conductive diamond) electrode of high concentration boron-doping.
To electrode 3 and reference electrode 4, as previously mentioned, tilt to insert fixing at the side wall portion 2b of determination unit 2 in the mode of active electrode 5 towards the bottom wall part 2c that is arranged at determination unit 2.So, electrode 3 and reference electrode 4 are tilted to insert fixing in the mode towards active electrode 5 at the side wall portion 2b of determination unit 2, therefore these electrodes 3,4 can be configured to not disturb surrounding structure.In addition, electrode 3 and reference electrode 4 are inserted in the insertion through hole 91H of stirrer 91 described later, the leading section of these electrodes 3,4 is near the electrode surface 5a of active electrode 5.
In addition, active electrode 5 is that bottom wall part 2c at determination unit 2 is so that the planar electrode that the mode that electrode surface 5a exposes at spatial accommodation 2S arranges.This active electrode 5 is set to be blocked in the peristome that bottom wall part 2c forms, and accordingly, forms the structure that electrode surface 5a exposes at spatial accommodation 2S.In addition, at bottom wall part 2c and active electrode 5 or keep between the holding member (not shown) of this active electrode 5, setting example is as the seal member of O type ring etc., for making the fluid sample that is contained in determination unit 2 not escape to outside from gap.
Be arranged at the rabbling mechanism 9 of said determination unit 2, as shown in Figure 1, there is the stirrer 91 in the spatial accommodation 2S that is contained in determination unit 2, the magnetic force operating mechanism 92 for this stirrer 91 is rotated by magnetic force.In addition, magnetic force operating mechanism 92 is arranged on the downside of the bottom wall part 2c of determination unit 2, particularly, is arranged on the downside of active electrode 5.
Stirrer 91, as shown in Figure 4 to 7, makes for the fluorine resin of such as PTFE etc., has and is body 911 cylindraceous and forms continuously the multiple blade parts 912 that extend along direction of principal axis at the axial side's of this body 911 open end 911p.In addition, because stirrer 91 is made for fluorine resin, be therefore resistant to pollution structure.In addition, although not shown, in stirrer 91, the bight of the bight of the radial outside of the opposing party's of body 911 open end 911q and the leading section of blade part 912 etc., being implemented chamfer machining (R chamfer machining) becomes the shape with fillet.Accordingly, stirrer 91 becomes the structure that is easy to rotation.
Axial the opposing party's of body 911 open end 911q has and is being housed inside under the state of determination unit 2, with the opposed opposed faces 911a of electrode surface 5a of active electrode 5.This opposed faces 911a is the circular face that is being formed by the open end of the opposing party's of body 911 open end 911q.
So, because body 911 is cylindric, in the rotating center section of stirrer 91, be formed for inserting to the insertion of electrode 3 and reference electrode 4 through hole 91H(with reference to Fig. 5).This insertion is rounded hole, cross section with through hole 91H.So, owing to being rounded hole, cross section, be under rotation status at stirrer 91, can make to insert large as much as possible to the insertion space of electrode 3 and reference electrode 4.
Multiple blade parts 912 equally spaced form at the circumferencial direction of a side's of body 911 open end 911p.In present embodiment, form 2 blade parts 912, the diametrically contraposition of its side's who is set at body 911 open end 911p.In addition, multiple blade parts 912 are phase parts of same shape each other.The end face 912x towards circumferencial direction of each blade part 912 is contained in the stirring face performance function (with reference to Fig. 4 and Fig. 5) of the fluid sample of spatial accommodation 2S as stirring.Further, the lateral surface 912m of blade part 912 is the same faces continuous with the outside circumference 911m of above-mentioned body 911.
In addition, at the body 911 of stirrer 91, multiple magnet 913 is built in inside.Consider the weight balancing of stirrer 91 entirety, multiple magnet 913 is arranged at the part (with reference to Fig. 5) that does not form blade part 912 on the circumferencial direction of body 911 axisymmetrically.Particularly, arrange respectively many at opposed walls 911s, the 911t of body 911 and be in bar-shaped magnet 913(Fig. 5, respectively arrange 3 at each opposed walls 911s, 911t).The bar-shaped magnet 913 that is built in each opposed walls 911s, 911t is set up (with reference to Fig. 6 and Fig. 7) along the direction of principal axis of body 911.Many bar-shaped magnet 913 that are arranged at a side opposed walls 911s are configured to direction of principal axis one side's side (blade part 912 sides) for the N utmost point, and axial another distolateral (opposed faces 911a side) is the S utmost point.In addition, many bar-shaped magnet 913 that are arranged at the opposing party's opposed walls 911t are configured to direction of principal axis one side's side (blade part 912 sides) for the S utmost point, and axial another distolateral (opposed faces 911a side) is the N utmost point.
For the stirrer 91 of formation like this, in the rotary body of magnetic force operating mechanism 92, in the part corresponding with the opposed walls 911s of one side, stirrer 91 sides being set is the magnet of the N utmost point, and in the part corresponding with above-mentioned the opposing party's opposed walls 911t, stirrer 91 sides being set is the magnet of the S utmost point.According to the magnetic force operating mechanism 92 of formation like this, Stirring 91 o'clock, attracted to state (, the opposed faces 911a of stirrer 91 is forced into the state of the surface of contact 2P described later) rotation of the magnet of rotary body with the magnet 913 of stirrer 91.So, stirrer 91 is attracted to rotary body, and opposed faces 911a rotates in the mode of sliding at surface of contact 2P, therefore can make the spin stabilization of stirrer 91.
In addition, the opposed faces 911a of stirrer 91, at axial the opposing party's of body 911 open end 911q, has formed 1 or multiple recess 914 for emit bubble to top that is.This recess 914 is the parts at interior lateral circle surface and the outside circumference opening of the opposing party's of body 911 open end 911q.In present embodiment, equally spaced form at the circumferencial direction of the opposing party's of body 911 open end 911q, consider the weight balancing of stirrer 91, be formed at the below (with reference to Fig. 6) of blade part 912.
The manufacture method of this stirrer 91 of simple declaration.As shown in Figure 8, the mode that is roughly axisymmetrically L word shape when mutual opposed side wall portion 901, the 902 distolateral direction of principal axis one that is processing forepiece 900 cylindraceous observation with direction from vertical with direction of principal axis respectively and excises is cut.Accordingly, form body 911 and blade part 912.In addition, form recess by axial another the distolateral open end at above-mentioned processing forepiece 900, discharge recess 914 for bubble thereby form.Further, be used for magnet 913 to be embedded in by cuttings such as end mills the hole of burying underground of body 911.Magnet 913 is embedded into this and buries hole underground.After having implemented processing like this, form stirrer 91 by implementing aforesaid R chamfer machining at processing back part.In addition, also can before imbedding magnet 913, implement R chamfer machining.
As shown in Fig. 9 and Figure 10, the determination unit 2 of present embodiment possesses stirrer surface of contact 2P(hereinafter referred to as surface of contact 2P) and keep face 2Q.Surface of contact 2P contacts with the opposed faces 911a of the stirrer 91 that is opposite to electrode surface 5a, and this opposed faces 911a is separated from electrode surface 5a.Maintenance face 2Q is forming with the diverse location of this surface of contact 2P, is the face different from opposed faces 911a in stirrer 91 face along its rotation, for keeping the rotation posture of stirrer 91.
Surface of contact 2P is that the opposed faces 911a in order to make stirrer 91 does not contact with electrode surface 5a and the face supported.This surface of contact 2P be from the electrode surface 5a of active electrode 5 towards electrode surface 5a towards direction (direction) separate the circular plane that is forming, mounting stirrer 91.Particularly, surface of contact 2P is on the top of the electrode surface 5a of active electrode 5, be formed on from the interior lateral circle surface 2x of determination unit 2 to radially inner side outstanding and form be circular teat 22.Particularly, formed with planes active electrode 5 opposition sides (upper surface) by teat 22.
As mentioned above, in such surface of contact 2P, stirrer 91 attracted magnetic force operating mechanism 92, and the opposed faces 911a of stirrer 91 is to be forced into the state rotation of surface of contact 2P.Accordingly, opposed faces 911a rotates in the mode of sliding at surface of contact 2P, therefore can make the spin stabilization of stirrer 91, can make the convection current of the fluid sample producing at electrode surface 5a according to stirrer 91 fix.
Maintenance face 2Q is that the turning axle of stirrer 91 is roughly fixing for electrode surface 5a, keeps the face of the rotation posture of stirrer 91.This maintenance face 2Q is at the surface of contact 2P(of determination unit 2 inside teat 22) upside form be cylindraceous.The central shaft of this maintenance face 2Q is roughly consistent with the rotary middle spindle of stirrer.Particularly, keep face 2Q to be formed by being of determination unit 2 interior lateral circle surface 2x cylindraceous.The roughly opposed formation in integrated spaced some gaps of the outside circumference 911m of the body 911 of this maintenance face 2Q and stirrer 91.In addition, the outside circumference 911m of body 911 and keep the gap between face 2Q, be preferably guaranteeing the degree of rotation of stirrer 91 as far as possible little, for example 0.5mm left and right.According to this maintenance face 2Q, can prevent stirrer 91 and reverse up and down in the time that rotation starts or in rotation way, suppress the vibration of the turning axle of stirrer 91, or the amplitude of the vibration of turning axle is reduced, can roughly keep regularly the rotation posture of stirrer 91.Therefore, can make the spin stabilization of stirrer 91, can make the convection current of the fluid sample producing at electrode surface 5a according to stirrer 91 roughly fixing.
In addition, in the present embodiment, the lateral surface 912m of the outside circumference 911m of body 911 and blade part 912 is the same face, keeps face 2Q to be configured to the lateral surface 912m(that is opposite to blade part 912 with reference to Figure 10).Accordingly, when stirrer 91 rotates, because the lateral surface 912m of blade part 912 is also along the interior lateral circle surface 2x that keeps face 2Q(determination unit 2) rotation, therefore can roughly keep regularly the rotation posture of stirrer 91.
(analytical approach of cadmium)
Then, the method that uses electrochemical analysis device 100 to analyze cadmium by leaching is described.
1. extract modulating process
Below, illustrate using rice as the situation that derives from biological sample.First, rice is pulverized and obtained ground rice.Then, the ground rice obtaining is dissolved in to perchloric acid, decomposing organic matter extracts cadmium on one side on one side.Thereby implement to attract to filter removal residue by the extract to obtaining.Further, attracting the extract after filtration to add Potassium Hydrogen Phthalate and NaOH, pH value is adjusted into 4.0 left and right as the extract of measuring for cadmium.
It should be noted that, in the extract of rice, cadmium forms the complex with copper conventionally.In the case of the complex of cadmium formation and copper, when stripping operation, observe sometimes the current peak being caused by the complex of cadmium and copper, and the current peak being caused by cadmium monomer, for the ease of analyzing, be preferably and only detect a kind of current peak being caused by cadmium.In addition, for the complex of cadmium monomer and cadmium and copper, the detection sensitivity difference of electrochemical analysis.Therefore, in order to make detection sensitivity consistent, be convenient to the discussion of analysis result, for using cadmium as detecting with the complex of copper, copper concentration in the extract of rice (does not for example reach benchmark concentration, for anticipation maximum concentration 4ppm) situation under, can add the not copper of full measure at extract and carry out supplementation with copper, in addition, also can (for example add greatly superfluous copper with the concentration of 3～10 times of left and right of the cadmium concentration of anticipation, the situation that is 50ppb for cadmium concentration, so that becoming the mode of 200～400ppb, concentration adds copper), using cadmium as detecting with the complex of copper.At this, in the time that said extracted liquid adds copper, can use CuCl
2deng copper compound.This copper compound, can add extract individually to, also can add together with perchloric acid, or add together with Potassium Hydrogen Phthalate.
2. electrode treatment process
By user's operating power ON/OFF button, calculation control device 8 makes the primary power of electrochemical analysis device 100 become ON.Thereafter, press bottom electrode treatment button by user, calculation control device 8 carries out in determinator, particularly, carries out the electrode processing controls of determination unit 2.This electrode treatment process is, first, use the feeding pipe 13 of liquid displacement mechanism 11, liquid used when cadmium will be extracted, for example perchloric acid, Potassium Hydrogen Phthalate, and the concentration of NaOH and the pH value O-phthalic acid buffer identical with extract are supplied in determination unit 2, and stir by magnetic rabbling mechanism 9 the O-phthalic acid buffer of supplying with on one side, (for example apply on schedule positive voltage at conductive diamond electrode 5 on one side, apply the voltage of 60 seconds+3.5V), remove the organism that adheres at conductive diamond electrode 5 and the electrode clean processing of heavy metal.Then, conductive diamond electrode 5 by predetermined time apply negative voltage (for example, apply 5 seconds-3.5V voltage), carry out the surperficial hydrogen end-blocking processing of conductive diamond electrode 5.Then, discharge this O-phthalic acid buffer from the discharge line 12 of liquid displacement mechanism 11, thereby complete electrode treatment process.
3. extract injection process
After above-mentioned electrode treatment process completes, user makes the open-close lid of the Sample introduction portion 21 that is arranged at cover C top move to release position, injects extract from Sample introduction portion 21.Then, user presses mensuration start button, and calculation control device 8 reception mensuration commencing signals start the mensuration of cadmium.It should be noted that, at this moment, obtain detection signal by detecting the liquid sensor (not shown) whether electrode 3, conductive diamond electrode 5 and reference electrode 4 are contacted with extract, calculation control device 8 judges whether electrode group 3～5 contacts with extract.If be judged as contact, enter into following mensuration work, if the wrong report showing etc. is carried out in not contact.
4. electro-deposition operation
Calculation control device 8 is to potentiostat PS output electro-deposition commencing signal.Accordingly, potentiostat PS makes the potential change of conductive diamond electrode 5 to the direction of negative potential, the current potential of this conductive diamond electrode 5 is for example become, than also low current potential (,-1.0V) of the reduction potential of cadmium, make cadmium electro-deposition in the surperficial 5a of conductive diamond electrode 5.At this, the in the situation that of cadmium and copper formation complex, can make the complex electro-deposition of cadmium and copper in the surperficial 5a of conductive diamond electrode 5.In this situation, can make electro-deposition current potential be-0.8V left and right.Keep the schedule time (for example, 10 minutes) to complete afterwards this electro-deposition operation state lower than above-mentioned reduction potential the current potential of conductive diamond electrode 5.
5. liquid displacement operation
After above-mentioned electro-deposition operation, potentiostat PS keeps fixing by the current potential of conductive diamond electrode 5 with the state lower than above-mentioned reduction potential.Under this state, calculation control device 8 is divided into repeatedly displacement by controlling liquid displacement mechanism 11 by the extract in determination unit 2 and O-phthalic acid buffer.In present embodiment, after the extract that is contained in determination unit 2 is discharged half by discharge line 12, supply with the O-phthalic acid buffer of the amount suitable with discharge rate by feeding pipe 13.For example, by repeatedly carrying out this work (4 left and right) extract is replaced into O-phthalic acid buffer.So, in liquid displacement operation, by the current potential of conductive diamond electrode 5 is kept to fixing with the state lower than above-mentioned reduction potential, can prevent that electro-deposition is in cadmium stripping in liquid displacement operation of electrode 5.At this, the quantity delivered of the discharge rate of extract and O-phthalic acid buffer can specify based on efflux time and service time respectively.
6. stripping operation (current detecting operation)
By above-mentioned liquid displacement operation, by after being replaced into phthalic acid damping fluid in determination unit 2, calculation control device 8, to potentiostat PS output stripping commencing signal.Accordingly, potentiostat PS to positive potential direction, particularly, is scanned up to the current potential higher than the reduction potential of cadmium (for example ,+1.0V) by the electric potential scanning of conductive diamond electrode 5, by the complex stripping of cadmium and copper to O-phthalic acid buffer.
Once the complex stripping of cadmium and copper, follows therewith, generation current at conductive diamond electrode 5 and between to electrode 3.The electric current being caused by the complex of cadmium and copper produces in this reactive system near+0.35V, and this electric current (electric signal) is sent to potentiostat PS, carries out control, the detection of the signal of each electrode.Here the signal being detected by potentiostat PS, is sent to calculation control device 8.Discharge O-phthalic acid buffer from the discharge line 12 of liquid displacement mechanism 11, thereby complete stripping operation.
Figure 11 represents an example of the volt-ampere characteristic being obtained by this stripping operation.In volt-ampere characteristic shown in Figure 11, near the current peak of observing-0.35v derives from the complex of cadmium and copper, and near the current peak of observing 0.25V derives from copper monomer.In addition, in the volt-ampere characteristic shown in Figure 11, the known concentration along with cadmium uprises, and the peak value of electric current also uprises.
One example of the volt-ampere characteristic obtaining in the situation that the acid using when on the other hand, Figure 12 is illustrated in modulation extract is hydrochloric acid.The in the situation that of using hydrochloric acid in the time of modulation extract, the residual organic matter not being decomposed becomes disturbing factor, in addition, due to cadmium and hydrochloric acid formation complex compound, as shown in figure 12, near the current peak (0.6V) that derives from cadmium is not obvious, thereby can not be by highly sensitive detection.
7. relation line production process
In present embodiment, analyze cadmium concentration for using standard addition method, use the sample that further adds the known cadmium standard model of concentration and become predetermined concentration (for example 50ppb) in the extract that is provided to above-mentioned electro-deposition operation～stripping operation, carry out electro-deposition operation～stripping operation similar to the above, make the relation line of cadmium concentration and current value or the quantity of electric charge.
8. cadmium concentration calculation process
Calculation control device 8, by the relation line contrast of the cadmium concentration of the current value obtaining or the quantity of electric charge and making and current value or the quantity of electric charge, calculates the cadmium concentration of extract.At this moment, only deduct in advance according to the current value from as measured value or the quantity of electric charge differential electrical flow valuve or the differential charge amount that the base current value measured with O-phthalic acid buffer or the basic quantity of electric charge obtain and calculate cadmium concentration, thereby can calculate cadmium concentration in degree of precision ground.The cadmium concentration so calculating is shown in the display part 801 of the front surface that is arranged on cover C.
9. rear electrowinning process
A period of time after the surface sweeping of current potential finishes, by by remain on+1.0V of the current potential of conductive diamond electrode 5, thereby make electro-deposition the whole strippings of cadmium, copper, can make 5 regeneration of conductive diamond electrode return to the state before mensuration.By regeneration conductive diamond electrode 5 like this, can reuse same electrode.At this, the regeneration of conductive diamond electrode 5, having more than is the maintenance by set potential, also can realize by carrying out the current potential multiple scanning of wide territory.
10. waste liquid operation
After above-mentioned rear electrowinning process, calculation control device 8 is replaced the extraction pump 122 of the discharge line 12 of mechanism 11 by controlling liquid, solution after the mensuration in determination unit 2 is discharged to waste liquid tank T2.After this waste liquid operation finishes, carry out the cleaning of determination unit, power supply is made as to OFF.
(effect of present embodiment)
According to the electrochemical determining device 100 of the present embodiment of formation like this, there is surface of contact 2P, this surface of contact 2P makes the electrode surface 5a of active electrode 5 separate with the opposed faces 911a of stirrer 91, therefore can be configured to stirrer 91 does not contact with active electrode 5, active electrode 5 can not cause damage by stirrer 91, and the electrostatic double layer that is formed at the electrode surface 5a of active electrode 5 can multilated yet.Accordingly, can improve the stability of electrochemical gaging.
In addition, there is the maintenance face 2Q of the rotation posture for keeping stirrer 91, therefore do not worry that stirrer 91 changes posture in rotary course, produce the rotation fault that contacts with active electrode 5 or can not rotate etc., can make rotational speed, the position of rotation of stirrer 91 stable, can make the spin stabilization of stirrer 91.Make accordingly the spin stabilization of stirrer 91, thereby the convection current of the fluid sample of the electrode surface 5a that can make at active electrode 5 is roughly fixing, can improves the stability of electrochemical gaging.
Moreover, according to the cadmium analytical approach of present embodiment, use perchloric acid to derive from biological sample extraction cadmium from rice etc., be contained in thereby can not form the complex compound of cadmium and decompose the organism that derives from biological sample, can carry out accurately the detection of cadmium and/or the mensuration of its concentration.
In addition, in present embodiment, use Potassium Hydrogen Phthalate as buffering agent, thereby measuring when cadmium, wrapped up by carboxyl as the metal of the lead of disturbing factor, selenium, chromium, boron etc., its result, is speculated as the interference having prevented cadmium.
Further, in the present embodiment, by comprising that electrode clean is processed and the electrode treatment process of hydrogen end-blocking processing, thereby the organism, the heavy metal that adhere to active electrode have been removed in advance, the surface of finishing conductive diamond electrode, thus analysis precision can further be improved.Especially, think in the present embodiment, generate CO free radical thereby carry out electrode clean processing in O-phthalic acid buffer by Ke Erbei reaction, this can effectively carry out organic decomposition, removal.
In addition, the invention is not restricted to above-mentioned embodiment.
For example, also can, in being of stirrer body cylindraceous, form blade part.In this situation, exist and insert the hidden danger diminishing with the opening size of through hole 91H, still can make the direction of principal axis size decreases of stirrer 91.
In addition, the maintenance face 2Q of above-mentioned embodiment is formed by the interior lateral circle surface 2x of determination unit 2, as shown in figure 13, also can be arranged between the interior lateral circle surface 2x of determination unit 2 and the outside circumference 911m of stirrer 91, arrange, lateral circle surface 10x is the distance member 10 of maintenance face 2Q in it.This distance member 10 has for being the cross section vertical with direction of principal axis the parts cylindraceous that equate cross sectional shape.At this, also can pass through to form from the interior lateral circle surface 10x of this distance member 10 to the outstanding cyclic lug of radially inner side, thereby become the device with surface of contact 2P.
Further, in the above-described embodiment, stirrer 91 is to have the device inserting with through hole 91H, but can be also not have the device inserting with through hole 91H.In this situation, can not will insert to active electrode 5 sides from the top of stirrer 91 electrode 3 and reference electrode 4, but for example can be also, make surface of contact 2P(teat 22) and the distance of active electrode 5 larger than above-mentioned embodiment, to electrode 3 and reference electrode 4 be inserted in spatial accommodation 2S to, be configured near that makes electrode 3 and reference electrode 4 be positioned at the electrode surface 5a of active electrode 5 from the sidewall between teat 22 and active electrode 5.
And, the maintenance face 2Q of above-mentioned embodiment be surround that the mode of the rotary middle spindle of stirrer 91 forms be cylindraceous, as shown in figure 14, can be also that the mode that is configured to be opposite to above-mentioned surface of contact 2P forms, rotatably clamp stirrer 91 with above-mentioned surface of contact 2P.As this maintenance face 2Q, also may be thought of as the circular plane that is for example contacting with the upper surface of stirrer 91.This maintenance face 2Q and above-mentioned surface of contact 2P similarly, are formed to the lower surface of the outstanding cyclic lug 23 of radially inner side by the interior lateral circle surface 2x from determination unit 2.At this, Figure 14 has represented to use the situation of bar-shaped stirrer 91, also can as embodiment described above, insert for having the stirrer of using through hole 91H.
And, in the above-described embodiment, be to possess active electrode 5, the device of being measured by three-electrode method to electrode 3 and reference electrode 4, but can be also only to possess active electrode 5 and the device of being measured by two electrode methods to electrode 3.Although can controlling, three-electrode method puts on active electrode 5 and the absolute value to the voltage between electrode 3, therefore can carry out precision and highly sensitive mensuration, but according to two electrode methods, the electrode using is only active electrode 5 and two electrodes to electrode 3, therefore can make simple structure, the miniaturization of determination unit 2.
In the cadmium analytical approach of above-mentioned embodiment, as the method for making of the relation line calculating for cadmium concentration, be not limited to standard addition method, copper concentration in extract is low, also can use inspection wire measurement to make in advance the relation line of cadmium concentration and current value or the quantity of electric charge.
Further, the electrochemical determining device of above-mentioned embodiment also can be applied to any or the multiple composition in the heavy metal ion that is determined at Cu, the As, Cd, the Zn etc. that contain in fluid sample.
In the cadmium analytical approach of above-described embodiment, although thereby can obtain by carrying out liquid displacement operation the signal that noise is little, also can not carry out liquid and replace operation and measure the heavy metal ion of cadmium etc.
In addition, the invention is not restricted to above-mentioned embodiment, only otherwise depart from the scope of spirit of the present invention, just can carry out various changes.
Claims (13)
1. an electrochemical analysis method, is characterized in that, is use derives from the cadmium containing in biological sample with electrochemical means analysis method to electrode and active electrode,
Possess abstraction process, add to deriving from biological sample the acid that there is oxidisability and do not form complex compound with cadmium, extract cadmium from above-mentioned deriving from biological sample.
2. electrochemical analysis method as claimed in claim 1, is characterized in that,
Possess pH value and adjust operation, the pH value of the extract obtaining from said extracted operation is adjusted into 3～7.
3. electrochemical analysis method as claimed in claim 1 or 2, is characterized in that,
Above-mentioned acid is perchloric acid.
4. electrochemical analysis method as claimed in claim 2 or claim 3, is characterized in that,
Adjust in operation in above-mentioned pH value, add the buffering agent being formed by organic acid and/or its salt at said extracted liquid.
5. the electrochemical analysis method as described in claim 1-4 any one, is characterized in that,
Possess copper and add operation, add copper above-mentioned in deriving from biological sample.
6. the electrochemical analysis method as described in claim 2-5 any one, is characterized in that,
Possess electrode clean operation, under the state contacting, apply positive voltage at above-mentioned active electrode at above-mentioned active electrode with solution, the said extracted liquid phase after the acid of above-mentioned solution and the composition of buffering agent and pH value and pH value are adjusted is same.
7. electrochemical analysis method as claimed in claim 6, is characterized in that,
Above-mentioned active electrode is conductive diamond electrode,
Possess hydrogen end-blocking chemical industry order, after above-mentioned electrode clean operation, apply negative voltage at above-mentioned conductive diamond electrode, make electrode surface hydrogen end-blocking.
8. an electrochemical analysis device, is characterized in that, is the device for derive from the cadmium that biological sample contains with electrochemical means analysis, possesses:
Extraction element, it adds to deriving from biological sample the acid that has oxidisability and do not form complex compound with cadmium, extracts cadmium from above-mentioned deriving from biological sample;
PH value adjuster, its pH value by the extract obtaining is adjusted into 3～7;
For built-in to electrode and active electrode, hold the unit of said extracted liquid;
Bringing device, it makes cadmium or its complex electro-deposition in the voltage of above-mentioned active electrode at above-mentioned active electrode and above-mentioned applying between to electrode, then, applies and makes electro-deposition in the voltage of the cadmium of above-mentioned active electrode or its complex stripping;
Pick-up unit, its detection results from above-mentioned active electrode and above-mentioned to the electric current between electrode.
9. electrochemical analysis device as claimed in claim 8, is characterized in that,
Possess copper adding set, it adds copper above-mentioned in deriving from biological sample.
10. electrochemical analysis device as claimed in claim 8 or 9, is characterized in that
Above-mentioned active electrode is conductive diamond electrode.
11. 1 kinds of reagent set, is characterized in that, for using when electrode and active electrode are derived to the cadmium that biological sample contains with electrochemical means analysis, extract this and derive from the cadmium in biological sample, and adjust the extract obtaining for mensuration,
This reagent set comprises the acid, buffering agent and the copper compound being made up of organic acid and/or its salt that have oxidisability and do not form complex compound with cadmium.
12. reagent set as claimed in claim 11, is characterized in that,
It is above-mentioned that to possess oxidisability and do not form the acid of complex compound with cadmium be perchloric acid.
13. reagent set as described in claim 11 or 12, is characterized in that,
Above-mentioned organic acid is phthalic acid or acetic acid.
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| CN103913490B (en) | 2018-10-16 |
| JP2014130031A (en) | 2014-07-10 |
| JP5759442B2 (en) | 2015-08-05 |
| CN109270132A (en) | 2019-01-25 |
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