CN102645477A - Iterative operation method for measuring concentration by aid of ion-selective electrode - Google Patents

Abstract

The invention discloses an iterative operation method for directly measuring concentration by the aid of an ion-selective electrode. By means of measuring the activity of ions in liquid to be measured, the iterative operation method based on a Davies formula is used for directly calculating the concentration of the ions. The iterative operation method overcomes the shortcoming that liquid to be measured and standard solution have the same ionic strength and pH (potential of hydrogen) in a traditional method needing adding high-concentration ionic strength modifiers and pH buffering agents into the liquid to be measured. Recent research discovers that measurement of electrode potential is strongly affected by ionic interaction, interaction of the ions and an electrode film and ionic dispersion force under the condition of high ionic strength, so that the original state of the liquid to be measured is damaged by the ionic strength and the pH in an adjusting system, and measuring results greatly deviate from a practical situation. The iterative operation method can exactly overcome the defects.

Description

Utilize the interative computation method of ion selecting electrode determining concentration

Technical field

The present invention relates to a kind of solution ion concentration assay method, particularly a kind of interative computation method of utilizing ion selecting electrode determining concentration.

Background technology

Because the ion-selective electrode range of application is very extensive, relates to every field such as scientific research, health care, food inspection and environmental monitoring.What but ion electrode was measured is the activity of ion, and measures the purpose concentration of ion often.The present invention proposes a kind of simple interative computation method and directly need not carry out any processing liquid to be measured by the activity calculating concentration.

The concentration (c) that the activity of effects of ion (a) equals this ion multiply by activity coefficient (γ), i.e. a _i=c _i* γ _iBecause activity coefficient is the function of total ionic strength adjustment buffer degree (I) in the solution, i.e. Davies formula:

${\mathrm{\γ}}_M=\exp (-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I}}{1+\sqrt{I}}-0.3I\right)---\left(1\right)$

Measure the concentration of liquid intermediate ion to be measured if desired, just must keep with titer in identical ionic strength.Solution commonly used has: 1) ionic homeostasis background method.In analytic liquid, except treating measured ion, also contain high and other the constant ions of a kind of concentration; 2) the buffering agent method of total ionic strength adjustment buffer degree calibration.The ionic strength adjustor that adds a kind of indifferent salt composition makes standard solution keep identical ionic strength with liquid to be measured, also adds the pH buffering agent sometimes, eliminates the hidden complexing agent of interference etc., to keep certain ionic strength and pH.

Different buffering agents not only possibly influence the mensuration result, and buffering effect and storage stability when different pH value are all different.Moreover various ISE method agents useful for same are while double as standard solution often, and each autogamy reagent can't be traced to the source as titer.And big quantity research in recent years shows, under high ionic strength, interionic interacts, the interaction of ion and electrode film, and the dispersion force of ion etc. all has intense influence to mensuration.Therefore, traditional when utilizing ion electrode to measure concentration, all destroyed the virgin state of liquid to be measured, make and measure precision and accuracy receives very big challenge.

Therefore, be badly in need of a kind of new method of utilizing the ion selecting electrode determining ion concentration, destroyed the defective of liquid status to be measured to overcome classic method.

Summary of the invention

In view of this, technical matters to be solved by this invention provides a kind of new method of utilizing the ion selecting electrode determining ion concentration, has destroyed the defective of liquid status to be measured to overcome classic method.

The objective of the invention is to realize like this:

The interative computation method of utilizing ion selecting electrode determining concentration provided by the invention may further comprise the steps:

S1: preparation concentration known and ion activity treat the measured ion standard solution;

S2: the electrode potential value that utilizes each ion in determination of electrode standard solution and the solution to be measured;

S3: according to the ion activity and the electrode potential value of standard solution, and the electrode potential value of effects of ion to be measured calculates the ion activity in the solution to be measured;

S4: according to each ion concentration value in the effects of ion activity iterative computation to be measured solution to be measured:

S5: export effects of ion concentration value to be measured.

Further, said step S3 specifically may further comprise the steps:

S31: ion activity and electrode potential value according to standard solution are drawn following typical curve:

Lna=kE+b, wherein, lna is the logarithm value of standard solution activity, and a is the ion activity of standard solution, and k is a slope, and b is an intercept, E is the electrode potential reading value on the ionometer;

S32: with the electrode potential value of the effects of ion to be measured of step S2 gained, the substitution typical curve calculates effects of ion activity to be measured.

Further, said step S4 specifically may further comprise the steps:

S41: calculate the initial concentration value of kation M, the initial concentration value of negative ion A through the effects of ion activity value of obtaining to be measured;

S42: carry out interative computation ionic strength value the n time by following formula according to the initial concentration value of kation M, the initial concentration value of negative ion A:

$I\left(n\right)=\frac{1}{2}(c_A^{(n-1)}{Z}_A^2+c_M^{(n-1)}{Z}_M^2),$

${\mathrm{\γ}}_M^{\left(n\right)}=\exp [-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I\left(n\right)}}{1+\sqrt{I\left(n\right)}}-0.3I\left(n\right))\right],$

Wherein, the ionic strength value of the n time interative computation of I (n) expression, T representes Kelvin temperature,

The concentration of representing the n-1 time i ion, Z _iThe quantivalency (comprising kation M and negative ion A) of expression i ion, Z _MThe quantivalency of expression M ion, the n value is a positive integer 1,2,3,4..., i represent the ionic species in the solution,

The activity coefficient of the n time superposition of M ion in the expression system;

S43: judge whether to satisfy following formula,, then return step S42 and repeat iterative process if do not satisfy:

I(n)-I(n-1))/I(n)＜thr；

Wherein, the ionic strength during the n-1 time iteration of I (n-1) expression, thr representes threshold value;

S44:, then stop iterative process if satisfy;

S45: by following formula with the concentration of iterative computation gained as solution concentration:

$c_M^{\left(n\right)}=\frac{a_M}{{\mathrm{\γ}}_M^{\left(n\right)}};$

$c_A^{\left(n\right)}=(v_{-}/v_{+}){c_M}^{\left(n\right)};$

Wherein, a _MBe the activity value of utilizing the M ion that electrode records,

Be the concentration value of the n time superposition of kation M,

It is the concentration value of the n time superposition of negative ion A; v _-The number of negative ion A during the expression electrolyte is formed, v ₊The number of kation M during the expression electrolyte is formed.

Further, the calculating of the initial concentration value of the initial concentration value of kation M, negative ion A specifically may further comprise the steps in the solution to be measured of said step S41:

S411: the effects of ion activity value to be measured that records among the step S32 is carried out the initial concentration value of interative computation kation M for the first time by following formula:

$c_M^{\left(0\right)}=a_M\mathrm{mol}/l,$

Wherein,

Be the initial concentration value of kation M, a _MIt is the activity value of utilizing the M ion that electrode records;

S412: carry out the initial concentration value of interative computation negative ion A for the first time by following formula according to the charge balance rule:

$c_A^{\left(0\right)}=(v_{-}/v_{+})a_M\mathrm{mol}/l$

Further, the iterative computation first time of kation M, negative ion A specifically may further comprise the steps in the solution to be measured of said step S42:

S421: carry out the interative computation ionic strength value first time according to following formula:

$I\left(1\right)=\frac{1}{2}(c_A^{\left(0\right)}{Z}_A^2+c_M^{\left(0\right)}{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{a}_M{Z}_A^2+a_M{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{Z}_A^2+Z_M^2)a_M,$

In the formula, I (1) expression is the ionic strength of interative computation for the first time.

S422: according to the initial activity coefficient of M ion in the Davies formula counting system:

${\mathrm{\γ}}_M^{\left(1\right)}=\exp [-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I\left(1\right)}}{1+\sqrt{I\left(1\right)}}-0.3I\left(1\right))\right],$

In the formula,

Expression M ion is the activity coefficient of iteration for the first time, and T representes Kelvin temperature, Z _MThe quantivalency of expression M ion;

S423: the concentration value that calculates M ion after the iteration for the first time through following formula:

$c_M^{\left(1\right)}=\frac{a_M}{{\mathrm{\γ}}_M^{\left(1\right)}}$

S424: the concentration according to A ion behind the charge balance rule calculating interative computation first time is:

$c_A^{\left(1\right)}=(v_{-}/v_{+})c_M^{\left(1\right)}\mathrm{mol}/l.$

The invention has the advantages that: what the present invention proposed is iterated through the Davies formula after proofreading and correct by ion activity, calculates the interative computation method of corresponding ion concentration, is applicable to the mensuration of the ion concentration under the different ionic strength condition.The correctness of this interative computation method is through checking theoretical and experiment.When utilizing ionometer to measure ion concentration, only need above-mentioned iterative program is write ionometer, just can realize utilizing the direct mensuration of ion-selective electrode to ion concentration.

The present invention utilizes the Davies formula to carry out interative computation through the mensuration to each ion activity in the liquid to be measured, directly calculates the concentration of ion.This method has overcome the ionic strength adjustor and the pH buffering agent that need in liquid to be measured, add high concentration in the classic method, makes between liquid to be measured and the standard solution to have identical ionic strength and the drawback of pH.Because under the high ionic strength condition; Interionic interacts; The interaction of ion and electrode film and the dispersion force of ion all affect the mensuration of electrode potential strongly; Therefore ionic strength in the regulation system and the virgin state that pH has destroyed liquid to be measured make the mensuration result depart from actual conditions more greatly.And the present invention just in time can overcome these defectives.

Other advantage of the present invention, target and characteristic will be set forth in instructions subsequently to a certain extent; And to a certain extent; Based on being conspicuous to those skilled in the art, perhaps can from practice of the present invention, obtain instruction to investigating of hereinafter.Target of the present invention and other advantage can be passed through following instructions, claims, and the structure that is particularly pointed out in the accompanying drawing realizes and obtains.

Description of drawings

In order to make the object of the invention, technical scheme and advantage clearer, will combine accompanying drawing that the present invention is made further detailed description below, wherein:

The process flow diagram of the ion selecting electrode determining ion concentration that Fig. 1 provides for the embodiment of the invention;

Fig. 2 utilizes ion-selective electrode directly to measure the structural representation of ion concentration for the hyperchannel ionometer that the embodiment of the invention provides based on the present invention.

Embodiment

Below will combine accompanying drawing, the preferred embodiments of the present invention will be carried out detailed description; Should be appreciated that preferred embodiment has been merely explanation the present invention, rather than in order to limit protection scope of the present invention.

Embodiment 1

The process flow diagram of the ion selecting electrode determining ion concentration that Fig. 1 provides for the embodiment of the invention; Fig. 2 utilizes ion-selective electrode directly to measure the structural representation of ion concentration for the hyperchannel ionometer that the embodiment of the invention provides based on the present invention; As shown in the figure: the interative computation method of utilizing the ion selecting electrode determining ion concentration provided by the invention may further comprise the steps:

S1: preparation concentration known and ion activity treat the measured ion standard solution;

S2: the electrode potential value that utilizes each ion in determination of electrode standard solution and the solution to be measured;

S3: according to the ion activity and the electrode potential value of standard solution, and the electrode potential value of effects of ion to be measured calculates the ion activity in the solution to be measured; Specifically may further comprise the steps:

S31: ion activity and electrode potential value according to standard solution are drawn following typical curve:

Lna=kE+b, wherein, lna is the logarithm value of standard solution activity, and a is the ion activity of standard solution, and k is a slope, and b is an intercept, E is the electrode potential reading value on the ionometer;

S32: with the electrode potential value of the effects of ion to be measured of step S2 gained, the substitution typical curve calculates effects of ion activity to be measured.

S4:, specifically may further comprise the steps according to each ion concentration value in the effects of ion activity iterative computation to be measured solution to be measured:

S41: calculate the initial concentration value of kation M, the initial concentration value of negative ion A through the effects of ion activity value of obtaining to be measured, specifically may further comprise the steps:

S411: the effects of ion activity value to be measured that records among the step S32 is carried out the initial concentration value of interative computation kation M for the first time by following formula:

$c_M^{\left(0\right)}=a_M\mathrm{mol}/l,$

Wherein,

Be the initial concentration value of kation M, a _MIt is the activity value of utilizing the M ion that electrode records;

S412: carry out the initial concentration value of interative computation negative ion A for the first time by following formula according to the charge balance rule:

$c_A^{\left(0\right)}=(v_{-}/v_{+})a_M\mathrm{mol}/l$

S42: the iterative computation first time of kation M, negative ion A specifically may further comprise the steps in the solution to be measured:

S421: carry out the interative computation ionic strength value first time according to following formula:

$I\left(1\right)=\frac{1}{2}(c_A^{\left(0\right)}{Z}_A^2+c_M^{\left(0\right)}{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{a}_M{Z}_A^2+a_M{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{Z}_A^2+Z_M^2)a_M,$

In the formula, I (1) expression is the ionic strength of interative computation for the first time.

S422: according to the initial activity coefficient of M ion in the Davies formula counting system:

${\mathrm{\γ}}_M^{\left(1\right)}=\exp [-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I\left(1\right)}}{1+\sqrt{I\left(1\right)}}-0.3I\left(1\right))\right],$

In the formula,

Expression M ion is the activity coefficient of iteration for the first time, and T representes Kelvin temperature, Z _MThe quantivalency of expression M ion;

S423: the concentration value that calculates M ion after the iteration for the first time through following formula:

$c_M^{\left(1\right)}=\frac{a_M}{{\mathrm{\γ}}_M^{\left(1\right)}}$

S424: the concentration according to A ion behind the charge balance rule calculating interative computation first time is:

$c_A^{\left(1\right)}=(v_{-}/v_{+})c_M^{\left(1\right)}\mathrm{mol}/l.$

S425: according to the concentration value of top calculating gained, the ionic strength and the activity coefficient of iteration are respectively so for the second time:

$I\left(2\right)=\frac{1}{2}(c_A^{\left(1\right)}{Z}_A^2+c_M^{\left(1\right)}{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{c}_M^{\left(1\right)}{Z}_A^2+c_M^{\left(1\right)}{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{Z}_A^2+Z_M^2)c_M^{\left(1\right)}=\frac{1}{2}(\frac{v_{-}}{v_{+}}{Z}_A^2+Z_M^2)\frac{a_M}{{\mathrm{\γ}}_M^{\left(1\right)}},$

${\mathrm{\γ}}_M^{\left(2\right)}=\exp [-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I\left(2\right)}}{1+\sqrt{I\left(2\right)}}-0.3I\left(2\right))\right],$

In the formula; The ionic strength of I (2) the expression interative computation first time,

expression M ion is the activity coefficient of iteration for the first time.The concentration value of M ion is after the iteration so for the second time:

$c_M^{\left(2\right)}=\frac{a_M}{{\mathrm{\γ}}_M^{\left(2\right)}},$

The concentration of A ion is behind the interative computation for the second time: $c_A^{\left(2\right)}=(v_{-}/v_{+})c_M^{\left(2\right)}\mathrm{Mol}/l;$

S426: carry out interative computation ionic strength value the n time by following formula according to the initial concentration value of kation M, the initial concentration value of negative ion A:

$I\left(n\right)=\frac{1}{2}(c_A^{(n-1)}{Z}_A^2+c_M^{(n-1)}{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{c}_M^{(n-1)}{Z}_A^2+c_M^{(n-1)}{Z}_M^2)$

$=\frac{1}{2}(\frac{v_{-}}{v_{+}}{Z}_A^2+Z_M^2)c_M^{(n-1)}=\frac{1}{2}(\frac{v_{-}}{v_{+}}{Z}_A^2+Z_M^2)\frac{a_M}{{\mathrm{\γ}}_M^{(n-1)}},$

${\mathrm{\γ}}_M^{\left(n\right)}=\exp [-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I\left(n\right)}}{1+\sqrt{I\left(n\right)}}-0.3I\left(n\right))\right],$

Wherein, the ionic strength of the n time interative computation of I (n) expression, T representes Kelvin temperature,

The concentration of representing A ion after the n-1 time iteration,

The concentration of representing M ion after the n-1 time iteration, Z _AThe quantivalency of expression A ion, Z _MThe quantivalency of expression M ion, the n value is a positive integer 1,2,3,4..., i represent the ionic species in the solution,

The activity coefficient of the n time superposition of M ion in the expression system;

S43: judge whether to satisfy following formula,, then return step S42 and repeat iterative process if do not satisfy:

I(n)-I(n-1))/I(n)＜thr；

Wherein, the ionic strength of the n time interative computation of I (n) expression, the ionic strength of the n-1 time interative computation of I (n-1) expression, thr representes threshold value, general value is less than 0.001.

S44: by following formula with the concentration of iterative computation gained as solution concentration:

$c_M^{\left(n\right)}=\frac{a_M}{{\mathrm{\γ}}_M^{\left(n\right)}};$

$c_A^{\left(n\right)}=(v_{-}/v_{+})c_M^{\left(n\right)};$

Wherein, a _MBe the activity value of utilizing the M ion that electrode records, Be the concentration value of the n time superposition of kation M,

It is the concentration value of the n time superposition of cation A; v _-The number of negative ion A during the expression electrolyte is formed, v ₊The number of kation M during the expression electrolyte is formed, establishing electrolyte is Mv ₊Av _-, its ionization reaction in water is so: Mv ₊Av _-=v ₊M+v _-A.

S45:, then stop iterative process if satisfy.

S5: export effects of ion concentration value to be measured.

Embodiment 2

That prepares known activity treats the measured ion standard solution.Concentration c is made as respectively: 10 ^-1Mol/l, 5 * 10 ^-2Mol/l, 10 ^-2Mol/l, 5 * 10 ^-3Mol/l, 10 ^-3Mol/l, 5 * 10 ^-4Mol/l, 10 ^-4Mol/l, 5 * 10 ^-5Mol/l;

1) supposition only contains a kind of electrolytical situation.If this electrolyte is Mv ₊4v _-, its ionization reaction in water is: Mv ₊Av _-=v ₊M+v _-A; So the activity of M ion can be measured by corresponding ISE in the WS.If the measured value of M ion activity is recorded as a _MMol/l, temperature is TK; Calculate the ion activity a of above-mentioned standard solution _M, concrete computing formula is following:

$a_M=c_M\·\exp [-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I}}{1+\sqrt{I}}-0.3I)\right]---\left(1\right)$

Wherein ionic strength I is:

Z _MBe the quantivalency of ion M, c _MBe the concentration of ion M,

Concentration for ion A.Utilize the electrode potential value (E) of each standard solution of determination of electrode and liquid to be measured.Utilize the logarithm value (lna of standard solution activity _M) (y axle) and corresponding electrode potential value (E) (x axle) make typical curve, obtains the straight line that meets Nernst equation, i.e. a lna _M=kE+b, wherein k is a slope, b is an intercept.With the electrode potential (E) of the liquid intermediate ion to be measured of gained, the substitution typical curve just can calculate the activity a of liquid intermediate ion to be measured.

2) the ion activity value that step 1) is recorded is as the initial concentration value of the interative computation M ion first time; Promptly

so; According to the charge balance rule, for the first time in the interative computation concentration of A ion should be

then for the first time the value of interative computation intermediate ion intensity be:

$I\left(1\right)=\frac{1}{2}(c_A^{\left(0\right)}{Z}_A^2+c_M^{\left(0\right)}{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{a}_M{Z}_A^2+a_M{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{Z}_A^2+Z_M^2)a_M---\left(2\right)$

Z _A, Z _MQuantivalency for ion A and M

By the Davies formula, can get the initial activity coefficient of M ion in system this moment:

${\mathrm{\γ}}_M^{\left(1\right)}=\exp [-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I\left(1\right)}}{1+\sqrt{I\left(1\right)}}-0.3I\left(1\right))\right]---\left(3\right)$

Then utilize (3) formula can obtain the concentration value of M ion after the iteration for the first time:

$c_M^{\left(1\right)}=\frac{a_M}{{\mathrm{\γ}}_M^{\left(1\right)}}---\left(4\right)$

According to the charge balance rule, the concentration of A ion should be

behind the interative computation for the first time

The ionic strength and the activity coefficient of iteration are respectively equally, for the second time:

$I\left(2\right)=\frac{1}{2}(c_A^{\left(1\right)}{Z}_A^2+c_M^{\left(1\right)}{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{c}_M^{\left(1\right)}{Z}_A^2+c_M^{\left(1\right)}{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{Z}_A^2+Z_M^2)c_M^{\left(1\right)}---\left(5\right)$

${\mathrm{\γ}}_M^{\left(2\right)}=\exp [-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I\left(2\right)}}{1+\sqrt{I\left(2\right)}}-0.3I\left(2\right))\right]---\left(6\right)$

The concentration value of M ion is after the iteration so for the second time:

$c_M^{\left(2\right)}=\frac{a_M}{{\mathrm{\γ}}_M^{\left(2\right)}}---\left(7\right)$

The concentration of A ion should be behind the interative computation for the second time $c_A^2=(v_{-}/v_{+})c_M^{\left(2\right)}\mathrm{Mol}/l.$

So iterate n time

$I\left(n\right)=\frac{1}{2}(c_A^{(n-1)}{Z}_A^2+c_M^{(n-1)}{Z}_M^2)$

$=\frac{1}{2}(\frac{v_{-}}{v_{+}}{c}_M^{(n-1)}{Z}_A^2+c_M^{(n-1)}{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{Z}_A^2+Z_M^2)c_M^{(n-1)}---\left(8\right)$

${\mathrm{\γ}}_M^{\left(n\right)}=\exp [-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I\left(n\right)}}{1+\sqrt{I\left(n\right)}}-0.3I\left(n\right))\right]---\left(9\right)$

To (I (n) I (n-1))/I (n)＜0.001 termination of iterations.Then last gained kation M and negative ion A concentration are:

$c_M^{\left(n\right)}=\frac{a_M}{{\mathrm{\γ}}_M^{\left(n\right)}}---\left(10\right)$

$c_A^{\left(n\right)}=(v_{-}/v_{+})c_M^{\left(n\right)}---\left(11\right)$

It is similar to contain multiple electrolytical situation, only need determine the activity of a kind of ion in every kind of electrolyte of system, just can calculate the ionic strength of first time during iteration:

$I\left(1\right)=\frac{1}{2}\underset{I}{\mathrm{\Σ}}{a}_i{Z}_i^2---\left(12\right)$

Calculate ion concentration according to above alternative manner then.At present the hyperchannel ionometer is accomplished, and has realized that multiple electrode measures simultaneously, collect the electrode potential value of each ion in liquid to be measured simultaneously, so the present invention also can computing for many electrolyte systems.

The above is merely the preferred embodiments of the present invention, is not limited to the present invention, and obviously, those skilled in the art can carry out various changes and modification and not break away from the spirit and scope of the present invention the present invention.Like this, belong within the scope of claim of the present invention and equivalent technologies thereof if of the present invention these are revised with modification, then the present invention also is intended to comprise these changes and modification interior.

Claims (5)

1. utilize the interative computation method of ion selecting electrode determining concentration, it is characterized in that: may further comprise the steps:

S1: preparation concentration known and ion activity treat the measured ion standard solution;

S2: the electrode potential value that utilizes each ion in determination of electrode standard solution and the solution to be measured;

S3: according to the ion activity and the electrode potential value of standard solution, and the electrode potential value of effects of ion to be measured calculates the ion activity in the solution to be measured;

S4: according to each ion concentration value in the effects of ion activity iterative computation to be measured solution to be measured:

S5: export effects of ion concentration value to be measured.

2. the interative computation method of utilizing ion selecting electrode determining concentration according to claim 1, it is characterized in that: said step S3 specifically may further comprise the steps:

S31: ion activity and electrode potential value according to standard solution are drawn following typical curve:

Lna=kE+b, wherein, lna is the logarithm value of standard solution activity, and a is the ion activity of standard solution, and k is a slope, and b is an intercept, E is the electrode potential reading value on the ionometer;

S32: with the electrode potential value of the effects of ion to be measured of step S2 gained, the substitution typical curve calculates effects of ion activity to be measured.

3. the interative computation method of utilizing ion selecting electrode determining concentration according to claim 1, it is characterized in that: said step S4 specifically may further comprise the steps:

S41: calculate the initial concentration value of kation M, the initial concentration value of negative ion A through the effects of ion activity value of obtaining to be measured;

S42: carry out interative computation ionic strength value the n time by following formula according to the initial concentration value of kation M, the initial concentration value of negative ion A:

$I\left(n\right)=\frac{1}{2}(c_A^{(n-1)}{Z}_A^2+c_M^{(n-1)}{Z}_M^2),$

${\mathrm{\γ}}_M^{\left(n\right)}=\exp [-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I\left(n\right)}}{1+\sqrt{I\left(n\right)}}-0.3I\left(n\right))\right],$

Wherein, the ionic strength value of the n time interative computation of I (n) expression, T representes Kelvin temperature,

The concentration of representing the n-1 time i ion, Z _iThe quantivalency (comprising ion M and ion A) of expression i ion, Z _MThe quantivalency of expression M ion, the n value is a positive integer 1,2,3,4..., i represent the ionic species in the solution,

The activity coefficient of the n time superposition of M ion in the expression system;

S43: judge whether to satisfy following formula,, then return step S42 and repeat iterative process if do not satisfy:

I(n)-I(n-1))/I(n)＜thr；

Wherein, the ionic strength during the n-1 time iteration of I (n-1) expression, thr representes threshold value, general value is less than 0.001;

S44:, then stop iterative process if satisfy;

S45: by following formula with the concentration of iterative computation gained as solution concentration:

$c_M^{\left(n\right)}=\frac{a_M}{{\mathrm{\γ}}_M^{\left(n\right)}};$

$c_A^{\left(n\right)}=(v_{-}/v_{+}){c_M}^{\left(n\right)};$

Wherein, a _MBe the activity value of utilizing the M ion that electrode records,

Be the concentration value of the n time superposition of kation M,

It is the concentration value of the n time superposition of negative ion A; v _-The number of negative ion A during the expression electrolyte is formed, v ₊The number of kation M during the expression electrolyte is formed.

4. the interative computation method of utilizing ion selecting electrode determining concentration according to claim 1 is characterized in that: the calculating of the initial concentration value of the initial concentration value of kation M, negative ion A specifically may further comprise the steps in the solution to be measured of said step S41:

S411: the effects of ion activity value to be measured that records among the step S32 is carried out the initial concentration value of interative computation kation M for the first time by following formula:

$c_M^{\left(0\right)}=a_M\mathrm{mol}/l,$

Wherein,

Be the initial concentration value of kation M, a _MIt is the activity value of utilizing the M ion that electrode records;

S412: carry out the initial concentration value of interative computation negative ion A for the first time by following formula according to the charge balance rule:

$c_A^{\left(0\right)}=(v_{-}/v_{+})a_M\mathrm{mol}/l,$

Wherein, the initial concentration value of

expression anionic ion A.

5. the interative computation method of utilizing ion selecting electrode determining concentration according to claim 1 is characterized in that: the iterative computation first time of kation M, negative ion A specifically may further comprise the steps in the solution to be measured of said step S42:

S421: carry out the interative computation ionic strength value first time according to following formula:

$I\left(1\right)=\frac{1}{2}(c_A^{\left(0\right)}{Z}_A^2+c_M^{\left(0\right)}{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{a}_M{Z}_A^2+a_M{Z}_M^2)=\frac{1}{2}(\frac{v_{-}}{v_{+}}{Z}_A^2+Z_M^2)a_M,$

In the formula, I (1) expression is the ionic strength of interative computation for the first time, Z _AThe quantivalency of expression negative ion A;

S422: according to the initial activity coefficient of M ion in the Davies formula counting system:

${\mathrm{\γ}}_M^{\left(1\right)}=\exp [-6030.2\×T^{-\frac{3}{2}}|Z_M^2\left|(\frac{\sqrt{I\left(1\right)}}{1+\sqrt{I\left(1\right)}}-0.3I\left(1\right))\right],$

In the formula,

Expression M ion is the activity coefficient of iteration for the first time, and T representes Kelvin temperature, Z _MThe quantivalency of expression kation M;

S423: the concentration value that calculates M ion after the iteration for the first time through following formula:

$c_M^{\left(1\right)}=\frac{a_M}{{\mathrm{\γ}}_M^{\left(1\right)}},$

S424: the concentration according to A ion behind the charge balance rule calculating interative computation first time is:

$c_A^{\left(1\right)}=(v_{-}/v_{+})c_M^{\left(1\right)}\mathrm{mol}/l,$

Wherein,

and

representes the concentration value of the first time behind the interative computation of kation M and negative ion A respectively.

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