CN101308113B - Lead ion selective electrode film using poly-1-aminoanthraquinone as carrier, its preparation method and uses thereof - Google Patents

Abstract

The invention discloses a membrane used for a lead ion selective electrode and taking a poly 1-aminoanthraquinone as a carrier, which is characterized in that: the membrane comprises poly 1-aminoanthraquinone, polyvinyl chloride and di-n-octyl phthalate. The invention also discloses a process for preparing the membrane used for the lead ion selective electrode and taking the poly 1-aminoanthraquinone as the carrier as well as purposes thereof.

Description

Membrane for lead ion selective electrode with poly-1-aminoanthraquinone as carrier, its preparation method and use

technical field

The invention relates to a film for a lead ion selective electrode with poly-1-aminoanthraquinone as a carrier, a preparation method and application thereof.

Background technique

An ion-selective electrode (ISE) is an electrochemical sensor and an important part of a potentiometric analysis system. The analysis technology based on ion selective electrode is to use the relationship between electrode potential and ion activity to realize the detection of ions. This technology has good selectivity, high sensitivity, fast analysis speed, low cost, wide range of analysis objects, and less sample consumption. features. With the continuous improvement and innovation of electrode membrane materials and manufacturing technology, ion selective electrode analysis technology has been widely used in environmental detection, industrial process control, clinical medicine, drug analysis and other fields.

With the rapid development of modern industry, many heavy metal ions have seriously polluted the environment. Heavy metal ions are difficult to be degraded by microorganisms. They can be latent in water and soil for a long time and enter plants, animals and even human bodies along the food chain. They accumulate in the human body and endanger the human body. healthy. Therefore, the detection of heavy metal ions is particularly important. The main methods for detecting heavy metal ions are spectrophotometry, atomic absorption method, stripping voltammetry, polarography, inductively coupled plasma mass spectrometry, etc. However, these methods have disadvantages such as expensive instruments and cumbersome operation, and it is difficult to realize online monitoring of heavy metal ions. The ion-selective electrode method is simple in operation, low in cost, fast in analysis speed, and easy to automate, and is especially suitable for field analysis and field automatic continuous detection. Therefore, it is of great significance to study ion-selective electrodes that can detect heavy metal ions.

Most of the research on heavy metal ion selective electrodes at home and abroad focuses on electrodes based on polyvinyl chloride (PVC) membranes, and the key to PVC membrane electrodes is to select appropriate ion carriers and realize the detection according to the selectivity of different carriers for metal ions. Neutral carriers including sulfides, crown ethers, and calixarenes have been extensively studied. In order to develop ion-selective electrodes with wider detection ranges, lower detection limits, and faster response speeds, researchers are still exploring the detection of heavy metals. Ions have better selectivity as carrier substances. Studies in recent years have found that some new conductive polymers have a strong ability to complex with heavy metal ions, especially some aromatic diamine polymers.

Contents of the invention

The purpose of the present invention is to solve the deficiencies in the prior art, to provide a film for lead ion selective electrode with poly-1-aminoanthraquinone as carrier, its preparation method and its application.

The film for lead ion selective electrode with poly-1-aminoanthraquinone as carrier is characterized in that it comprises poly-1-aminoanthraquinone, polyvinyl chloride and di-n-octyl phthalate.

Wherein, the weight ratio of poly-1-aminoanthraquinone, polyvinyl chloride and dioctyl phthalate is 1:(10-50):(30-100).

Among them, an anion exclusion agent is also included.

Wherein, the weight ratio of poly-1-aminoanthraquinone, polyvinyl chloride, di-n-octyl phthalate and anion removing agent is 1:(10-50):(30-100):(1-10).

Wherein, the anion exclusion agent is selected from sodium tetraphenylborate, potassium tetraphenylborate, potassium tetrakis(4-chlorophenyl)boride and the like.

Preferably, the film thickness is 0.07mm-0.30mm.

A method for preparing a film for a lead ion selective electrode with poly-1-aminoanthraquinone as a carrier, characterized in that poly-1-aminoanthraquinone, polyvinyl chloride and di-n-octyl phthalate are mixed in an organic solvent , fully dispersed, and after the solvent volatilizes, the film for lead ion selective electrode with poly-1-aminoanthraquinone as the carrier is prepared.

Wherein, the organic solvent is selected from tetrahydrofuran, chloroform, dichloromethane, acetone and the like.

Wherein, the weight ratio of poly-1-aminoanthraquinone, polyvinyl chloride and dioctyl phthalate is 1:(10-50):(30-100).

Among them, an anion exclusion agent is also included.

Wherein, the weight ratio of poly-1-aminoanthraquinone, polyvinyl chloride, di-n-octyl phthalate and anion removing agent is 1:(10-50):(30-100):(1-10).

Wherein, the anion exclusion agent is selected from sodium tetraphenylborate, potassium tetraphenylborate or potassium tetrakis(4-chlorophenyl)boride.

The lead ion selective electrode membrane with poly-1-aminoanthraquinone as the carrier is used for detecting the concentration of lead ions in the solution.

The lead ion selective electrode film with poly-1-aminoanthraquinone as carrier is used to detect the concentration of lead ions in the solution, and it is characterized in that the poly-1-aminoanthraquinone described in claims 1-5 is used as carrier The lead ion selective electrode film is used to make the detection electrode, and the entire detection electrode is composed as follows:

Internal reference electrode (Ag/AgCl) | 0.1mol L ^-1 lead nitrate solution | membrane for lead ion selective electrode with poly-1-aminoanthraquinone as carrier | solution to be tested | salt bridge | external reference electrode (SCE)

First measure 5-10 groups of standard solutions with known lead ion concentrations respectively, and according to the measurement results, take the electrode response potential EMF as the ordinate and lg[C] as the abscissa, and draw the relationship curve between EMF and lg[C], namely Obtain working curve, when measuring the solution of unknown lead ion concentration, measure its response potential EMF value, can know lead ion concentration according to its relationship curve; Wherein, in lg[C], C represents lead ion concentration.

Wherein, the pH value of the solution to be tested is 2.8-5.2.

Among the present invention, PAAQ is poly-1-aminoanthraquinone, and PVC is polyvinyl chloride; DOP is di-n-octyl phthalate; THF is tetrahydrofuran; NaTPB is sodium tetraphenylborate; EMF in the accompanying drawing is measured Electrode response potential.

In the present invention, the lead ion selective electrode film with poly-1-aminoanthraquinone as the carrier has a detection performance ahead of the electrodes reported in China, and also has a certain competitive advantage with the electrodes reported in the world, specifically reflected in:

(1) The selected ionophore poly-1-aminoanthraquinone is prepared by a simple chemical oxidation synthesis method, with simple equipment and high yield, and the 1-aminoanthraquinone monomer is a common chemical product in China, with abundant sources and low price Inexpensive, so that the developed electrode has a lower cost.

(2) It has a good Nernst response to lead ions, a wide linear range (2.5×10 ^-6 -1.0×10 ^-1 mol·L ^-1 ) and a low detection limit (7.8×10 ^{- 7} mol·L ^-1 ), and has a Nernst response slope that is more consistent with the theoretical value.

(3) It has an extremely fast response speed, the response time is only 12s, which can realize the rapid detection of lead ions.

(4) It has good selectivity. Alkali metal ions (Na ⁺ , K ^+, etc.) and alkaline earth metal ions (Ba ²⁺ , Ca ^{2+ ,} etc.) basically do not interfere with the electrodes, and the interference coefficients are far less than 1.

The lead ion selective electrode membrane with poly-1-aminoanthraquinone as the carrier has a wide linear range, a low detection limit and a fast response speed. At the same time, the electrode has good selectivity and is not interfered by other cations. smaller. In addition, the synthesis method of the carrier material poly-1-aminoanthraquinone is simple, the source of raw materials is wide, and the cost is low. The lead ion-selective electrode developed with poly-1-aminoanthraquinone as the carrier has greater competitive advantages in similar electrodes and has broad application prospects.

Description of drawings

Fig. 1 is the impact of the amount of carrier PAAQ on the potential response of the electrode;

Fig. 2 is composed of PAAQ: PVC: DOP: the influence of the thickness of the ion-selective membrane of NaTPB=1: 33: 66: 1 on the electrode potential response;

Fig. 3 is the relation of the response potential of electrode and the pH value of three concentration lead ion solutions;

Figure 4 is the response time of a membrane electrode composed of PAAQ:PVC:DOP:NaTPB=1:33:66:1 and a thickness of 0.09mm

Fig.5 Response potential of the membrane electrode in the presence of various interfering ions at a concentration of 1×10 ^-3 mol·L ^-1 ;

Figure 6 is the potentiometric titration curve of 1.00×10 ^-3 mol·L ^-1 Pb(NO ₃ ) ₂ solution titrated with 1.00×10 ^-3 mol·L ^-1 EDTA;

Detailed ways

The reagents used in the present invention are all analytically pure, and the re-distilled deionized water is used for the configuration solution. 1-aminoanthraquinone, ammonium persulfate, Shanghai Qingxi Chemical Technology Co., Ltd.; polyvinyl chloride (PVC), Shanghai Chlor-Alkali Chemical Co., Ltd.; di-n-octyl phthalate (DOP), Sinopharm Chemical Reagent Co., Ltd. ; Tetrahydrofuran (THF), Shanghai Lingfeng Chemical Reagent Co., Ltd.; sodium tetraphenylborate (NaTPB), Sinopharm Chemical Reagent Co., Ltd.; lead nitrate, Sinopharm Chemical Reagent Co., Ltd.

Preparation of lead nitrate standard solution

Weigh 3.31g of lead nitrate and place it in a beaker, dissolve it with double-distilled deionized water, pour it into a 100mL volumetric flask, add heavy-distilled deionized water to the mark line, and prepare a 0.1mol·L ^- 1 lead nitrate solution. Lead nitrate standard solutions of other concentrations were prepared using the stepwise dilution method. For example, pipette 10 mL of 0.1 mol·L ^-1 lead nitrate solution into a 100 mL volumetric flask, and distill deionized water to the mark with heavy weight to obtain 0.01 mol·L ^-1 lead nitrate solution. The solution can be prepared by serially diluting to 10 ^-8 mol·L ^-1 .

Preparation of carrier poly-1-aminoanthraquinone

Poly-1-aminoanthraquinone (PAAQ) was prepared by chemical oxidation synthesis. Weigh 2mmol (446mg) 1-aminoanthraquinone monomer, put it into a 100ml beaker, add 40ml of acetonitrile, and pipette perchloric acid into the beaker, so that the concentration of perchloric acid in the acetonitrile solution is 0.05mol/L. In addition, accurately weigh 2 mmol (456 mg) of ammonium persulfate as an oxidizing agent with an analytical balance, dissolve it in 0.75 mL of deionized water, and place the two beakers containing the monomer solution and the oxidizing agent in a constant temperature water bath at 20°C. Then drop the oxidant solution into the monomer solution at a rate of 1 drop/3 seconds, and at the same time, the monomer should be stirred on a magnetic stirrer. After the oxidant is dripped, react at a constant temperature under the magnetic stirrer for 24 hours. After the reaction, the system was centrifuged, and the solid product was washed with absolute ethanol and then dried at 50°C.

Example 1

Weigh respectively 8 mg of poly-1-aminoanthraquinone (PAAQ), 200 mg of polyvinyl chloride (PVC), 400 mg of di-n-octyl phthalate (DOP), and 8 mg of sodium tetraphenylborate (NaTPB), and add these four reagents beaker, and added 5mL of tetrahydrofuran, intermittent ultrasonic dissolution for 1 hour. Then the mixed solution is poured on the flat bottom glass and left for 24 hours. After the THF is completely volatilized, a tough and elastic film is obtained. The composition of the film is PAAQ: PVC: DOP: NaTPB=1: 25: 50: 1, The thickness of the film was 0.16 mm. A disc with a diameter of about 16 mm is cut from the obtained film, and is glued to a PVC pipe end with an inner diameter of 13 mm and an outer diameter of 15 mm with epoxy resin. Fill the tube with 0.1mol·L ^-1 Pb(NO3)2 reference solution, and insert an Ag/AgCl electrode as the internal reference electrode. Before use, the electrode was activated with 10 ^-3 mol·L ^-1 lead nitrate solution for 12 hours, and then washed with distilled deionized water until the potential value was stable.

Example 2

Weigh respectively poly-1-aminoanthraquinone (PAAQ) 6.06mg, polyvinyl chloride (PVC) 200mg, dioctyl phthalate (DOP) 400mg, sodium tetraphenylborate (NaTPB) 6.06mg, these four kinds The reagent was added to the beaker, and 5 mL of tetrahydrofuran was added, and dissolved by intermittent ultrasonication for 1 hour. Then the mixed solution is poured on the flat bottom glass and left for 24 hours. After the THF is completely volatilized, a tough and elastic film is obtained. The composition of the film is PAAQ: PVC: DOP: NaTPB=1: 33: 66: 1, The thickness of the film was 0.16 mm. A disc with a diameter of about 16 mm is cut from the obtained film, and is glued to a PVC pipe end with an inner diameter of 13 mm and an outer diameter of 15 mm with epoxy resin. Fill the tube with 0.1mol·L ^-1 Pb(NO ₃ ) ₂ reference solution, and insert an Ag/AgCl electrode as the internal reference electrode. Before use, the electrode was activated with 10 ^-3 mol·L ^-1 lead nitrate solution for 12 hours, and then washed with distilled deionized water until the potential value was stable.

Example 3

Weigh 4mg of poly-1-aminoanthraquinone (PAAQ), 200mg of polyvinyl chloride (PVC), 400mg of di-n-octyl phthalate (DOP), 4mg of sodium tetraphenylborate (NaTPB), and add these four reagents beaker, and added 5mL of tetrahydrofuran, intermittent ultrasonic dissolution for 1 hour. Then the mixed solution is poured on the flat bottom glass and left for 24 hours. After the THF is completely volatilized, a tough and elastic film is obtained. The composition of the film is PAAQ: PVC: DOP: NaTPB=1: 50: 100: 1, The thickness of the film was 0.16 mm. A disc with a diameter of about 16 mm is cut from the obtained film, and is glued to a PVC pipe end with an inner diameter of 13 mm and an outer diameter of 15 mm with epoxy resin. Fill the tube with 0.1mol·L ^-1 Pb(NO ₃ ) ₂ reference solution, and insert an Ag/AgCl electrode as the internal reference electrode. Before use, the electrode was activated with 10 ^-3 mol·L ^-1 lead nitrate solution for 12 hours, and then washed with distilled deionized water until the potential value was stable.

Example 4

Weigh respectively poly-1-aminoanthraquinone (PAAQ) 6.06mg, polyvinyl chloride (PVC) 200mg, dioctyl phthalate (DOP) 400mg, sodium tetraphenylborate (NaTPB) 6.06mg, these four kinds The reagent was added to the beaker, and 5 mL of tetrahydrofuran was added, and dissolved by intermittent ultrasonication for 2 hours. Then pour the mixed solution on the flat bottom glass and let it stand for 24 hours. After the tetrahydrofuran is completely volatilized, a tough and elastic film is obtained, and the thickness of the film is 0.22mm. A disc with a diameter of about 16 mm is cut from the obtained film, and is glued to a PVC pipe end with an inner diameter of 13 mm and an outer diameter of 15 mm with epoxy resin. Fill the tube with 0.1mol·L ^-1 Pb(NO ₃ ) ₂ reference solution, and insert an Ag/AgCl electrode as the internal reference electrode. Before use, the electrode was activated with 10 ^-3 mol·L ^-1 lead nitrate solution for 12 hours, and then washed with distilled deionized water until the potential value was stable.

Example 5

Weigh respectively poly-1-aminoanthraquinone (PAAQ) 6.06mg, polyvinyl chloride (PVC) 200mg, dioctyl phthalate (DOP) 400mg, sodium tetraphenylborate (NaTPB) 6.06mg, these four kinds The reagent was added to the beaker, and 5 mL of tetrahydrofuran was added, and dissolved by intermittent ultrasonication for 1 hour. Then pour the mixed solution on the flat bottom glass and let it stand for 24 hours. After the tetrahydrofuran is completely volatilized, a tough and elastic film is obtained, and the thickness of the film is 0.16mm. A disc with a diameter of about 16 mm is cut from the obtained film, and is glued to a PVC pipe end with an inner diameter of 13 mm and an outer diameter of 15 mm with epoxy resin. Fill the tube with 0.1mol·L ^-1 Pb(NO ₃ ) ₂ reference solution, and insert an Ag/AgCl electrode as the internal reference electrode. Before use, the electrode was activated with 10 ^-3 mol·L ^-1 lead nitrate solution for 12 hours, and then washed with distilled deionized water until the potential value was stable.

Example 6

Weigh respectively poly-1-aminoanthraquinone (PAAQ) 6.06mg, polyvinyl chloride (PVC) 200mg, dioctyl phthalate (DOP) 400mg, sodium tetraphenylborate (NaTPB) 6.06mg, these four kinds The reagent was added to the beaker, and 5 mL of tetrahydrofuran was added, and the solution was ultrasonically dissolved intermittently for 0.5 hours. Then pour the mixed solution on the flat bottom glass and let it stand for 24 hours. After the tetrahydrofuran is completely volatilized, a tough and elastic film is obtained, and the thickness of the film is 0.09mm. A disc with a diameter of about 16 mm is cut from the obtained film, and is glued to a PVC pipe end with an inner diameter of 13 mm and an outer diameter of 15 mm with epoxy resin. Fill the tube with 0.1mol·L ^-1 Pb(NO ₃ ) ₂ reference solution, and insert an Ag/AgCl electrode as the internal reference electrode. Before use, the electrode was activated with 10 ^-3 mol·L ^-1 lead nitrate solution for 12 hours, and then washed with distilled deionized water until the potential value was stable.

Sodium tetraphenylborate in the above examples can be replaced by potassium tetraphenylborate or potassium tetrakis(4-chlorophenyl)borate; tetrahydrofuran can be replaced by chloroform, dichloromethane or acetone, etc.

Determination of potential

The potential was measured using a PHS-3C pH meter produced by Shanghai Kangyi Instrument Co., Ltd. The external reference electrode is a 217-type double-junction saturated calomel electrode, and the salt bridge is a 0.1mol·L ^-1 KCl solution. The entire electrode is composed as follows: internal reference electrode (Ag/AgCl) | 0.1mol L ^-1 lead nitrate solution | lead ion selective electrode membrane with poly-1-aminoanthraquinone as carrier | solution to be tested | salt bridge | external reference Specific electrode (SCE)

Specific test method: the solution to be tested is a Pb(NO ₃ ) ₂ standard solution with a concentration of 10 ^-8 -10 ^-1 mol·L ^-1 . Measure 20mL of a certain concentration of Pb(NO ₃ ) ₂ solution in a beaker, connect the external reference electrode and membrane electrode to the pH meter, and adjust the pH meter to the electromotive force measurement position. Place the external reference electrode and membrane electrode in the solution to be tested, and record the stable potential value when the potential response is stable.

When investigating the applicable range of the pH value of the electrode, HNO ₃ and NaOH were used to adjust the pH value of the solution.

When investigating the response time of the electrode, the time from when the recording membrane electrode is in contact with the solution to be tested with different concentrations to when the potential reaches equilibrium is the response time of the electrode.

Example 7-9

By changing the amount of carrier PAAQ to study the effect of electrode film on electrode performance. Fig. 1 is the potential response curve of the membrane electrode prepared under three different dosages of the carrier PAAQ to lead ions, and the corresponding electrode performance parameters are shown in Table 1. It can be seen that the membrane electrodes under the three carrier dosages all show good Nernstian responses to lead ions, but their performance parameters as lead ion selective electrodes are quite different. Among them, the electrode with the carrier content in the middle and the composition of PAAQ:PVC:DOP:NaTPB=1:33:66:1 showed the best Nernst response, with a slope of 28.1mV·decade ^-1 , close to the energy The theoretical value of the Stern slope is 29.6mV·decade ^-1 , the linear range is wide, 4.0×10 ^-6 -1.0×10 ^-1 mol·L ^-1 , and the lower detection limit can reach 1.86×10 ^-6 mol·L ^-1 .

Table 1 Performance parameters of lead ion selective electrodes with PAAQ as the carrier under different membrane compositions

PAAQ: PVC: DOP: NaTPB (weight ratio) Linear range/(mol L ^-1 ) linear equation Slope/(mV·decade ^-1 ) Lower limit of detection/(mol·L ^-1 ) Response time/s 1:25:50:1 1.0×10 ^-5 -1.0×10 ^-1 E＝129.6-26.71g[C] 26.7 3.29×10 ^-6 16 1:50:100:1 1.0×10 ^-5 -2.4×10 ^-2 E＝112.6-27.91g[C] 27.9 2.92×10 ^-6 17 1:33:66:1 4.0×10 ^-6 -1.0×10 ^-1 E＝126.1-28.1lg[C] 28.1 1.86×10 ^-6 14

Examples 10-12

The composition of the selected membrane is PAAQ:PVC:DOP:NaTPB=1:33:66:1, the potential response of the electrode prepared with three sensitive membranes with different thicknesses is shown in Figure 2, and the corresponding electrode performance parameters are listed in Table 2 . It is found that as the thickness of the sensitive film decreases, the performance parameters of the electrode also increase. The Nernst response slope of the electrode with a sensitive film thickness of 0.09mm is 28.9mV·decade ^-1 , which is closest to the theoretical value of the Nernst slope. Its detection linear range is 2.5×10 ^-6 -1.0×10 ^-1 mol·L ^-1 . Compared with the electrode with a sensitive film thickness of 0.22 mm, the linear range is nearly an order of magnitude wider, and its detection lower limit is also among all electrodes. The lowest value can reach 7.76×10 ^-7 mol·L ^-1 .

The composition of table 2 different thicknesses is the performance parameter of the film for lead ion selective electrode of PAAQ: PVC: DOP: NaTPB=1: 33: 66: 1

Film thickness/mm Linear range/(mol L ^-1 ) linear equation Slope/(mV·decade ^-1 ) Lower limit of detection/(mol·L ^-1 ) Response time/s 0.22 1.0×10 ^-5 -1.0×10 ^-1 E＝120.5-28.7lg[C] 28.7 4.47×10 ^-6 15 0.16 4.0×10 ^-6 -1.0×10 ^-1 E＝126.1-28.1lg[C] 28.1 1.86×10 ^-6 14 0.09 2.5×10 ^-6 -1.0×10 ^-1 E＝132.5-28.9lg[C] 28.9 7.76×10U ^-7 12

Examples 13-15

The relationship between potential response and pH value of a membrane electrode with a composition of PAAQ:PVC:DOP:NaTPB=1:33:66:1 and a thickness of 0.09mm in three different concentrations of lead ion solutions is shown in Figure 3. When the pH value is less than 2.8, the potential fluctuates greatly with the change of pH value. When the pH value is greater than 5.2, the potential fluctuates greatly with the change of pH value. The pH range of the electrode is 2.8-5.2, within this range The response potential of the electrode is not affected by the pH value, beyond this range, the potential fluctuates with the change of the pH value. The influence of pH value on the electrode is mainly manifested in two aspects, one is the influence on the hydrolysis state of lead ions, and the other is the influence on the complexation behavior of the carrier to lead ions. When the pH value is high, Pb ²⁺ is easily combined with OH ^- to form Pb(OH) ⁺ and Pb(OH) ₂ , resulting in a decrease in the concentration of free Pb ²⁺ in the solution, thereby causing a change in potential; when the pH value is low, The high concentration of H ⁺ can easily protonate the N in the carrier poly-1-aminoanthraquinone, and even cause desorption by ion exchange with the complexed Pb ²⁺ , which reduces the complexing ability of the carrier to lead ions, causing The electrodes respond to changes in potential.

Examples 16-18

The relationship between the potential response and time of the membrane electrode with the composition of PAAQ:PVC:DOP:NaTPB=1:33:66:1 and a thickness of 0.09mm in three different lead ion concentrations is shown in Figure 4. It can be seen that under three different Pb ²⁺ concentrations, the response potential of the electrode can reach stability within 12s, and the response speed is very fast, which is close to the fastest response speed of the lead ion selective electrode reported in the literature. Because poly-1-aminoanthraquinone has the ability to quickly complex lead ions, and its intrinsic conductivity is conducive to the transmission of charges in the film, which reduces the internal resistance of the film, thus endowing the electrode with a fast response speed. The electrode can be used for at least 2 months without any change in its performance parameters, and its linear range and Nernst response slope remain the same as before.

Example 19

Selectivity is an important index to measure the ion selective electrode. An ideal ion-selective electrode should only have a Nernst response to a specific ion, but in fact other coexisting ions in the measured solution will interfere with the electrode response. The potential selectivity coefficient K _{i, j} ^Pot is usually used to measure the selectivity of the electrode, which is defined as the ratio of the activity of the ion to be measured α _i and the activity of the interfering ion α _j that can produce the same potential when other test conditions are the same ,Right now $K_{i,j}^{\mathrm{Pot}}={\mathrm{\α}}_i/{\mathrm{\α}}_j.$ K _{i, j} ^Pot represents the contribution of interfering ions in the mixed solution to the potential of the ion-selective electrode, and the smaller the value, the better the selectivity of the electrode. The methods for measuring the potential selectivity coefficient include the separate solution method (SSM) and the fixed interference method (FIM). The separate solution method generally measures the solution containing only main ions and the solution containing only interference ions through electrodes, and according to the equipotential response Point the concentration ratio of the main ion and the interference ion to obtain the potential selectivity coefficient; and the fixed interference method is to change the concentration of the main ion under the concentration of the fixed interference ion to measure, according to the lower limit of detection of the main ion by the electrode and compared with the fixed interference The ion concentration was used to obtain the potential selectivity coefficient. Since the separate solution method is only applicable when the electrode is strictly in Nernst response, it cannot reflect the actual situation that the electrode is used in the coexistence of interfering ions and ions to be measured in the same test solution, so the fixed interference method is often used to determine the potential selectivity coefficient .

The present invention adopts the fixed interference method to measure the selectivity coefficient of the electrode, and the concentration of the interfering ions is fixed at 1×10 ^-3 mol·L ^-1 . The relationship between the potential response of the studied electrodes in the presence of various interfering ions and the concentration of lead ions is shown in Figure 5, and the calculated potential selectivity coefficients are shown in Table 3. It can be seen from Table 3 that alkali metal ions (Na ⁺ , K ^+, etc.) and alkaline earth metal ions (Ba ²⁺ , Ca ^{2+ ,} etc.) basically do not interfere with the electrodes, and the interference coefficients are all below 8×10 ^-3 , Far less than 1, it shows that the studied ion selective membrane electrode with PAAQ as the carrier has good selectivity to lead ions.

Table 3 Potential selectivity coefficients of electrodes for various interfering ions (concentration of interfering ions is fixed at 1×10 ^-3 mol·L ^-1 )

Interfering ions Potential selectivity coefficient KP _{b2+, B} ^POT _NH4 ⁺ 7.59×10 ^-3 Na ⁺ 7.18×10 ^-3 K ⁺ 4.27×10 ^-3 Ba ²⁺ 3.55×10 ^-3 Ca ²⁺ 3.09×10 ^-3

Select an electrode whose film composition is PAAQ:PVC:DOP:NaTPB=1:33:66:1, and whose thickness is 0.09mm, and use it as an indicator electrode for EDTA potentiometric titration of lead ions. Titrate 10.00 mL of 1.00×10 ^-3 mol·L ^-1 Pb(NO ₃ ) ₂ standard solution with 1.00×10 ^-3 mol·L ^-1 EDTA. The titration curve is shown in Figure 6, and the potentiometric titration curve does not show the standard S-type, which may be caused by the interference of Na ⁺ in the EDTA solution. When some lead ion selective electrodes reported in the literature are used as indicator electrodes for EDTA potentiometric titration of lead ions, their potentiometric titration curves show a pattern similar to that shown in Figure 6; moreover, it can still be observed from Figure 6 that Pb ²⁺ - The mutation position of the corresponding stoichiometric point of the EDTA complex, which indicates that the lead ion selective membrane electrode with PAAQ as the carrier can be used as the indicator electrode for the potentiometric titration of lead ions.

The above-mentioned embodiments are only used to illustrate the present invention, and do not constitute a limitation on the scope of the claims. Other substantially equivalent means conceivable by those skilled in the art are within the scope of the claims of the present invention.

Claims (11)

1. Take poly-1-aminoanthraquinone as the film for lead ion selective electrode of carrier, it is characterized in that, comprise poly-1-aminoanthraquinone, polyvinyl chloride and di-n-octyl phthalate, poly-1-aminoanthraquinone , the weight ratio of polyvinyl chloride and di-n-octyl phthalate is 1: (10～50): (30～100), and the described lead ion selective electrode film with poly 1-aminoanthraquinone as carrier adopts The following method is prepared: mix poly-1-aminoanthraquinone, polyvinyl chloride and 2-n-octyl phthalate in an organic solvent, fully disperse, and obtain after the solvent evaporates. 2. the film for lead ion selective electrode with poly-1-aminoanthraquinone as carrier according to claim 1, is characterized in that, also comprises anion exclusion agent, and described anion exclusion agent is selected from sodium tetraphenylborate, tetraphenyl borate Potassium phenyl borate, potassium tetrakis (4-chlorophenyl) boride. 3. take poly-1-aminoanthraquinone as the film for lead ion selective electrode of carrier according to claim 2, it is characterized in that poly-1-aminoanthraquinone, polyvinyl chloride, dioctyl phthalate and The weight ratio of the anion exclusion agent is 1:(10-50):(30-100):(1-10). 4. The film for lead ion selective electrode using poly-1-aminoanthraquinone as a carrier according to any one of claims 1-3, characterized in that the film thickness is 0.07mm-0.30mm. 5. prepare the method for the lead ion selective electrode membrane that is carrier with poly-1-aminoanthraquinone, it is characterized in that poly-1-aminoanthraquinone, polyvinyl chloride and dioctyl phthalate are mixed and placed in organic In the solvent, fully dispersed, after the solvent volatilizes, the lead ion selective electrode film with poly-1-aminoanthraquinone as the carrier is obtained, and the weight of poly-1-aminoanthraquinone, polyvinyl chloride and di-n-octyl phthalate The ratio is 1:(10-50):(30-100). 6. the preparation according to claim 5 takes poly-1-aminoanthraquinone as the method for the lead ion selective electrode membrane of carrier, it is characterized in that, described organic solvent is selected from tetrahydrofuran, chloroform, dichloromethane, acetone. 7. the preparation according to claim 5 is the method for the lead ion selective electrode film of carrier with poly-1-aminoanthraquinone, it is characterized in that, also add anion exclusion agent, described anion exclusion agent is selected from tetraphenylboron Sodium, Potassium tetraphenylborate, Potassium tetrakis(4-chlorophenyl)boride. 8. the preparation according to claim 7 is the method for the lead ion selective electrode film of carrier with poly-1-aminoanthraquinone, it is characterized in that, poly-1-aminoanthraquinone, polyvinyl chloride, phthalic acid dinormal The weight ratio of the octyl ester to the anion-removing agent is 1: (10-50): (30-100): (1-10). 9. The film for lead ion selective electrode with poly-1-aminoanthraquinone as carrier according to any one of claims 1-4 is used to detect the concentration of lead ions in the solution. 10. The lead ion selective electrode film with poly-1-aminoanthraquinone as carrier according to claim 9 is used to detect the concentration of lead ions in the solution, it is characterized in that it comprises the steps of: applying any one of claims 1-4 The lead ion-selective electrode film with poly-1-aminoanthraquinone as the carrier is used to make the detection electrode, and the entire detection electrode is composed as follows: Internal reference electrode Ag/AgCl | 0.1mol L ^-1 lead nitrate solution | membrane for lead ion selective electrode with poly-1-aminoanthraquinone as carrier | solution to be tested | salt bridge | external reference electrode SCE First measure 5-10 groups of standard solutions with known lead ion concentrations respectively, and according to the measurement results, take the electrode response potential EMF as the ordinate and lg[C] as the abscissa, and draw the relationship curve between EMF and lg[C], namely Obtain working curve, when measuring the solution of unknown lead ion concentration, measure its response potential EMF value, can know lead ion concentration according to its relationship curve; Wherein, in lg[C], C represents lead ion concentration. 11. The film for lead ion selective electrode using poly-1-aminoanthraquinone as carrier for detecting lead ion concentration according to claim 9 or 10, characterized in that the pH value of the solution to be tested is 2.8-5.2.

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