CN109459420B

CN109459420B - Method for detecting di/ferric iron ions in water body

Info

Publication number: CN109459420B
Application number: CN201811631214.3A
Authority: CN
Inventors: 赖家平; 冯焕然; 单法硕; 孙慧
Original assignee: South China Normal University
Current assignee: South China Normal University
Priority date: 2018-12-29
Filing date: 2018-12-29
Publication date: 2021-06-04
Anticipated expiration: 2038-12-29
Also published as: CN109459420A

Abstract

The invention belongs to the technical field of analysis methods, and particularly relates to a method for detecting di/ferric ions in a water body. The invention discloses a fluorescent probe-ellagic acid capable of carrying out valence state analysis on iron element, which is provided withLow cost, easy obtaining, and the uniqueness advantage that most fluorescent probes do not have, namely, the iron ions Fe with two valence states²⁺And Fe³⁺Both have response to form two complexes, and the Fe can be respectively qualitatively and quantitatively measured in Tris-HCl buffer solution²⁺And Fe³⁺The concentration of (c); and masking Fe in diammonium tartrate³⁺Can still accurately detect Fe²⁺. Whether quantitative detection alone or Fe masking³⁺In the case of quantitative detection, the fluorescence emission intensity of ellagic acid and the concentration of iron ions have good linear relationship, and the detection limits are 72nM, 63nM and 76nM respectively. By utilizing the characteristic, the ellagic acid can be used for simultaneously analyzing iron ions with different valence states in the water body, so that the fluorescence analysis method is also applied to valence state analysis.

Description

Method for detecting di/ferric iron ions in water body

Technical Field

The invention belongs to the technical field of analysis methods, and particularly relates to a method for detecting di/ferric ions in a water body.

Background

Iron not only has important industrial application, but it is also the most abundant trace element in human body. As the most abundant trace element in the body, iron plays an important role in many physiological processes. Iron is not only an important component of hemoglobin, but it also helps the cytochrome to redox transfer electrons. In addition, iron is an important component of nitrogenase. However, too high a content of iron may cause serious health problems such as causing cancer and aging of some organs such as heart, pancreas and liver, neurological diseases such as parkinsonism and senile dementia. The iron in the organism is mainly divalent, and the iron is trivalent in a very small amount, so the trivalent iron is usually harmful to the organism, but the iron in the natural water body is just trivalent. Therefore, environmental science has attracted attention to finding a method for rapid qualitative and quantitative detection and valence state analysis of iron energy.

The existing methods for detecting iron (or ferrous) ions include colorimetry, electrochemical analysis, high performance liquid chromatography, spectrophotometry, atomic absorption method and the like. These detection methods, while each having advantages, also have certain disadvantages or are precise and expensive instruments; or the sample has more components and large interference; or the detection limit is high; or cumbersome to operate, etc. Therefore, these methods have certain limitations in application, and most of the fluorescent probes cannot analyze the valence state of the same element.

Discovering content

In order to overcome the defects of the prior art, the invention aims to provide a method for detecting di/ferric ions in a water body.

In order to achieve the above object, the technical solution adopted by the present discovery is as follows:

a method for detecting di/ferric ions in a water body comprises the following steps:

(1) taking a water sample to be detected, adding hydroxylamine hydrochloride into the water sample to ensure that Fe in the solution³⁺All reduced to Fe²⁺Adding Tris-HCl buffer solution and methanol to obtain solution I, and adding Na into the solution I₂EA to obtain a solution II, detecting the fluorescence emission intensity of the solution II according to F₁＝-1099.47c₁+4241.78 Linear regression equation for Fe in solution²⁺With Fe³⁺Wherein, F₁As intensity of fluorescence emission, c₁Is Fe²⁺With Fe³⁺(ii) total concentration of (d);

(2) when Fe²⁺/Fe³⁺When the concentration ratio is more than 0.07, another part of water sample to be detected is taken, diammonium tartrate is added into the water sample to be detected to obtain a solution III, Tris-HCl buffer solution and methanol are added into the solution III to obtain a solution IV, and Na is added into the solution IV₂EA to give a solution V, and detecting the fluorescence emission intensity of the solution V according to F₂＝-1078.43c₂+4297.06 Linear regression equation for Fe in solution²⁺A concentration of (b) then c₂Is Fe in the water sample to be measured²⁺C is a concentration of₁-c₂Is Fe in the water sample to be measured³⁺Wherein, F₂Is the fluorescence emission intensity;

when Fe²⁺/Fe³⁺Concentration ratio of 0 or less07, taking another part of water sample to be detected, adding moxifloxacin to obtain a solution VI, adding a Tris-HCl buffer solution to the solution VI to obtain a solution VII, and detecting the fluorescence emission intensity of the solution VII to be F₃(ii) a Adding moxifloxacin into distilled water to obtain a moxifloxacin blank solution, and detecting the fluorescence intensity of the moxifloxacin blank solution to be F₀According to F₀－F₃＝1868.12*c₃ ^1/2Calculating Fe in the solution by a linear regression equation of-467.71³⁺A concentration of (b) then c₃Is Fe in the water sample to be measured³⁺C is a concentration of₁-c₃Is Fe in the water sample to be measured²⁺The concentration of (c).

It should be noted that, because the linear ranges of ellagic acid and moxifloxacin are not consistent, it is sometimes necessary to dilute solution I by a certain factor until the total iron concentration is within the linear range of ellagic acid and then add ellagic acid, so when diluting solution I, according to the linear regression equation F₁＝-1099.47c₁+4241.78 calculated Fe²⁺The concentration of (c) needs to be multiplied by the dilution factor to be the actual concentration of total iron in the actual sample.

Preferably, the concentration of Tris-HCl buffer in the solution I in the step (1), the solution IV in the step (2) and the solution VII is 0.01M.

Preferably, the volume fraction of methanol in the solution I in the step (1) and the solution IV in the step (2) is 80%.

Preferably, in the solution II in the step (1) and the solution V in the step (2), Na is added₂The concentration of EA was 8. mu.M.

Preferably, in the solution III in the step (2), the concentration of diammonium tartrate is 0.01M.

Preferably, in the solution VI in the step (2), the concentration of the moxifloxacin is 2 mu M.

Preferably, the concentration of the moxifloxacin in the blank solution of the moxifloxacin in the step (2) is 2 μ M.

Preferably, the detection conditions of the fluorescence emission intensity of the detection solution II in the step (1) and the fluorescence emission intensity of the detection solution V in the step (2) are that the fluorescence emission intensity in the wavelength range of 377-650 nm is recorded under the conditions of 357nm as the excitation wavelength, 5nm excitation slit, 5nm emission slit and 700V photomultiplier voltage.

Preferably, after adding the Tris-HCl buffer solution and the methanol in the step (1) and after adding the Tris-HCl buffer solution and the methanol in the step (2) to the solution III, the pH value of the solution is adjusted to be 5-7.

Said Na₂EA is the disodium salt of ellagic acid, wherein ellagic acid has the structural formula shown below:

preferably, the method for detecting the di/ferric ions in the water body is suitable for Fe²⁺Or Fe³⁺The concentration of (a) is in the range of 0.08-1.10 mu M.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the invention discloses a fluorescent probe- -ellagic acid capable of carrying out valence state analysis on iron element, which has the characteristics of low cost and easy acquisition, and has the unique advantage that most of fluorescent probes do not have, namely, iron ions Fe with two valence states²⁺And Fe³⁺Both respond to form two complexes, ellagic acid and Fe²⁺Coordination ratio of 1:3 to Fe³⁺The coordination ratio is 1: 2. Respectively qualitatively and quantitatively measuring Fe in Tris-HCl buffer solution with pH of 6.5²⁺And Fe³⁺The concentration of (c); and masking Fe in diammonium tartrate³⁺Can still accurately detect Fe²⁺. Whether quantitative detection alone or Fe masking³⁺Under the condition of (1), the quantitative detection has good linear relation, the linear range is 0.08-1.1 mu M, and the detection limits are 72nM, 63nM and 76nM respectively. By utilizing the characteristic, the ellagic acid can be used for simultaneously analyzing iron ions with different valence states in the water body, so that the fluorescence analysis method is also applied to valence state analysis.

Drawings

FIG. 1 is a graph showing fluorescence emission intensity of solutions containing different metal ions in example 1.

FIG. 2 is a graph of the fluorescence emission intensity of four methanol-water phase solutions of example 1.

FIG. 3 shows the blank solution and Fe content for different volume fractions of methanol in example 1²⁺、Fe³⁺A plot of fluorescence emission intensity versus solution; wherein, three continuous columns form a group and correspond to the same volume fraction of methanol, and the three columns sequentially correspond to EA, EA + Fe from left to right³⁺、EA+Fe²⁺And (3) solution.

FIG. 4 shows that in the case of example 2, in which a single interfering ion is present, Fe is not added²⁺Or Fe³⁺And adding Fe²⁺And Fe³⁺The fluorescence emission intensity of the solution of (a); wherein, three continuous columns form a group and correspond to the same interfering ions, and the three columns sequentially correspond to EA + interfering ions, EA + interfering ions and Fe from left to right³⁺EA + interfering ion + Fe²⁺And (3) solution.

FIG. 5 shows that in example 2, in the presence of mixed interfering ions, Fe was not added²⁺Or Fe³⁺And adding Fe²⁺And Fe³⁺A fluorescence emission intensity map of the solution of (a); the 4 curves sequentially correspond to EA, EA + interfering ions + Fe from top to bottom²⁺EA + interfering ion + Fe³⁺And (3) solution.

FIG. 6 is a graph of fluorescence emission intensity of solutions at different pH values in example 3.

FIG. 7 shows fluorescence emission intensity and Fe of Probe EA in example 4²⁺Is shown in linear relationship with concentration of (1).

FIG. 8 shows fluorescence emission intensity and Fe of Probe EA in example 4³⁺Is shown in linear relationship with concentration of (1).

FIG. 9 is the masking of Fe in example 4³⁺Fluorescence emission intensity of Probe EA and Fe²⁺Is shown in linear relationship with concentration of (1).

FIG. 10 shows the results of determination of EA and Fe probes in example 5²⁺Job's plot of the stoichiometric ratio.

FIG. 11 shows the results of determination of EA and Fe probes in example 5³⁺Job's plot of the stoichiometric ratio.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto. For process parameters not specifically noted, reference may be made to conventional techniques.

The reagents and equipment used in the following examples are as follows:

reagent:

ellagic acid (analytically pure, Shanghai Michelin reagent Co., Ltd.)

Amino tert-butanetriol (99.9%, Shanghai Biotechnology engineering service Co., Ltd.)

Methanol (analytically pure, Chengdu city Kelong chemical reagent factory)

Tartaric acid (analytically pure, Shanghai Michelin reagent Co., Ltd.)

Diammonium tartrate (analytically pure, Shanghai Mielin reagent Co., Ltd.)

Hydrochloric acid (analytically pure, Chengdu Kelong chemical reagent factory)

Aqueous solutions of various metal ions (including Al)³⁺、Be²⁺、Ba²⁺、Li⁺、Mg²⁺、Cu²⁺、Cd²⁺、Co2+、Pb²⁺、Ag⁺、Cr³ ⁺、Ni²⁺、Zn²⁺、Mn²⁺、Hg²⁺、Fe²⁺、Fe³⁺) Are each prepared from its corresponding nitrate or hydrochloride salt (analytical grade, Shanghai Aladdin reagent)

Tris-HCl and Tris-tartaric acid buffer solutions with various pH values are prepared from amino tert-butanetriol and hydrochloric acid or amino tert-butanetriol and tartaric acid;

except for special instructions, the used reagents are analytically pure; the water used is deionized water; all reagents were purchased from commercial suppliers and used without further purification.

The instrument comprises the following steps:

analytical balance (FA2004B, Shanghai Tianmei balance apparatus Co., Ltd.)

Fluorescence spectrophotometer (FL-2700, Hitachi, Japan Co., Ltd.)

PH meter (PHS-3C, Shanghai precision scientific instruments Co., Ltd., Reye instrument factory)

Vortex mixer (XW-80A, Shanghai Jingke industry Co., Ltd.)

Liquid-transfering gun 50 muL/100 muL/1 mL/5mL (Beijing Dalongxing laboratory instruments Co., Ltd.)

Microfiltration membrane (Water system, diameter 50mm, aperture 0.2 μm Jinteng microfiltration membrane)

Example 1

This example provides an experiment for investigating the selectivity of EA to metal ions, and an experiment for investigating the influence of the volume fraction of methanol on the results of EA detection of metal ions.

Using Tris-HCl buffer solution with pH 7.0 and concentration 0.01M as solvent, Na with concentration of 8 μ M was prepared₂EA solution, then adding 1 equivalent of metal ion Al to the solution³⁺、Be²⁺、Ba²⁺、Li⁺、Mg²⁺、Cu²⁺、Cd²⁺、Co²⁺、Pb²⁺、Ag⁺、Ni²⁺、Zn²⁺、Fe²⁺、Fe³⁺、Mn²⁺、Cr³⁺、Hg²⁺Meanwhile, blank solutions to be tested were prepared, and the change in fluorescence emission intensity of each solution was measured, with the results shown in fig. 1.

As can be seen from FIG. 1, Fe²⁺With Fe³⁺For Na₂EA solution has obvious fluorescence quenching effect, Cr³⁺There is also partial quenching. The results show that Na₂EA solution to Fe²⁺And Fe³⁺All have good selectivity, remove Cr³⁺Besides some interference, other ions do not interfere, so only Cr needs to be eliminated³⁺The interference of (2) is sufficient. Through analysis, Fe²⁺And Fe³⁺Make Na₂Quenching of EA fluorescence occurs because the carbonyl oxygen and phenolic hydroxyl groups of the acid phenolic lactone react with Fe respectively²⁺And Fe³⁺A complexing effect occurs because of Cr³⁺And Fe³⁺Some similarity in structure, so Na is also present in aqueous systems₂EA fluorescence was quenched.

To eliminate Cr³⁺Interference to the above-mentioned Na₂Adding methanol into EA solution to make methanol volume be 66.67% of total volume of solution, using it as detection solution, respectively detecting blank solution, adding Fe²⁺Solution of (2), addition of Fe³⁺And adding an equivalent amount of Cr³⁺The fluorescence intensity of the solution (2) is shown in FIG. 2.

As can be seen from FIG. 2, after addition of methanol, Cr was added³⁺The interference of (2) can be eliminated.

In order to search for the optimal volume fraction of methanol, 50%, 60%, 70%, 80%, 90%, and 95% EA, EA + Fe of methanol were prepared³⁺、EA+Fe²⁺Solution, EA and Fe in solution²⁺、Fe³⁺The fluorescence intensity of each solution was measured at a concentration of 8. mu.M, and the results are shown in FIG. 3.

As can be seen from FIG. 3, when the volume fraction of methanol is not less than 50%, Fe is contained²⁺、Fe³⁺The fluorescence intensity of the solution (A) is relatively close to that of the blank solution, but when the volume fraction of methanol is 80%, the blank solution and the solution containing Fe are relatively close to each other²⁺、Fe³⁺The difference in fluorescence intensity of the solution reaches the highest value.

Example 2

This example provides an anti-interference study of the process of detecting di/ferric ions with an EA fluorescent probe.

To explore Na₂EA vs. Fe in solid water samples²⁺With Fe³⁺Whether there is practical detectability, other metal ions (Al) need to be examined³⁺、Be²⁺、Ba²⁺、Li⁺、Mg²⁺、Cu²⁺、Cd²⁺、Co²⁺、Pb²⁺、Ag⁺、Cr³⁺、Ni²⁺、Zn²⁺、Mn²⁺、Hg²⁺) For determination of Fe² ⁺With Fe³⁺The interference of (2). Thus, in a test solution with a pH of 7.0, a concentration of Tris-HCl buffer solution of 0.01M and a methanol volume fraction of 80%, Na was detected₂When the concentration of EA and the concentration of interference metal ions are both 32 mu M, Fe is not added²⁺Or Fe³⁺And is addedFe²⁺(concentration 8. mu.M) and Fe³⁺The fluorescence emission intensity of the solution (concentration: 8. mu.M) is shown in FIG. 4.

As can be seen from FIG. 4, 4 equivalents of any single coexisting ion do not interfere with the fluorescence quenching of EA, i.e., the presence of a single coexisting interfering ion does interfere with EA and Fe²⁺、Fe³⁺The coordination effect of (2) does not affect. This demonstrates EA vs. Fe²⁺、Fe³⁺The selectivity of (a) is not affected.

In order to investigate whether the mixed ions will interfere the selectivity, the 15 interfering ions and Fe were designed in the experiment²⁺、Fe³⁺The mixed solution of (1). Preparation of Na₂When the concentration of EA and the concentration of mixed ions are both 8 mu M, no Fe is added in the detection²⁺Or Fe³⁺And adding Fe²⁺(concentration 8. mu.M) and Fe³⁺The fluorescence emission intensity of the solution (concentration: 8. mu.M) is shown in FIG. 5.

As can be seen from FIG. 5, the fluorescence intensity of the solution containing 15 mixed ions was similar to that of the blank solution, but Fe was added²⁺Or Fe³⁺After that, the fluorescence intensity was still significantly quenched. The results show that: common mixed metal ion pairs Na₂EA determination of Fe²⁺And Fe³⁺All without interference.

Example 3

This example provides pH vs. EA detection of Fe²⁺And Fe³⁺Study of the effects of (c).

Due to pH value to Fe²⁺And Fe³⁺And the existence form of EA has obvious influence, and then the fluorescence emission intensity of EA and Fe are influenced²⁺And Fe³⁺The influence of this experiment on the pH value was investigated as follows. In a test solution with a concentration of 0.02M in Tris-HCl buffer solution and a volume fraction of 80% methanol, when the pH values are 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 and 7.0, respectively, and Na₂EA and Fe²⁺、Fe³⁺When the concentration of (A) was 8. mu.M, the fluorescence emission intensity of each solution was measured, and the results are shown in FIG. 6.

As can be seen from FIG. 6, when the pH value is 2.5-5.0, the fluorescence emission intensity is dependent onQuenching begins with increasing pH; adding Fe when the pH value is 5.0-7.0²⁺Or Fe³⁺The fluorescence emission intensity of the post EA was clearly quenched and stable.

Example 4

This example provides Fe²⁺And Fe³⁺Quantitative detection study of (3).

(1)Fe²⁺And Fe³⁺Individual quantitative detection of

To explore EA and Fe²⁺With Fe³⁺Whether quantitative relation exists or not, a series of detection solutions with EA concentration of 8 mu M and Fe volume fraction are designed in a detection solution with pH of 6.5, Tris-HCl buffer concentration of 0.01M and methanol volume fraction of 80 percent²⁺、Fe³⁺The results of measuring the fluorescence emission intensity changes of the blank and the mixed solution at concentrations of 0.08. mu.M, 0.09. mu.M, 0.1. mu.M, 0.2. mu.M, 0.3. mu.M, 0.4. mu.M, 0.5. mu.M, 0.6. mu.M, 0.7. mu.M, 0.8. mu.M, 0.9. mu.M, 1.0. mu.M, and 1.1. mu.M, respectively, with 357nm as the excitation wavelength, 5nm excitation slit, 5nm emission slit, and 700V photomultiplier voltage are shown in FIGS. 7 and 8.

As can be seen from FIGS. 7 and 8, the fluorescence emission intensity of probe EA varies with Fe²⁺With Fe³⁺Quenching by increasing concentration, and Fe² ⁺With Fe³⁺When the concentration is 0.08-1.10 mu M, the fluorescence emission intensity of the probe EA and the Fe²⁺With Fe³⁺All in a linear relationship. The linear regression equation is obtained as F ═ 1099.47c +4241.78 (R)²0.9985) and F1080 c +4108.52 (R)²0.9987), wherein F represents fluorescence emission intensity, and c represents Fe²⁺Or Fe³⁺The concentration of (D) (unit: μ M). When the signal-to-noise ratio is 3, according to the formula: 3 σ/k, giving detection limits of 72nM and 63 nM. Due to Fe³⁺Hydrolysis degree is larger at pH value larger than 4, so fluorescence quenching degree is higher than that of Fe²⁺Low, i.e. amplitude, in comparison with Fe²⁺Is not obvious.

(2)Fe²⁺And Fe³⁺Masking Fe in coexistence³⁺To Fe under the premise of²⁺Quantitative detection of

To explore Fe²⁺And Fe³⁺Whether EA can still act on Fe in coexistence²⁺Quantitative determination was carried out by designing a series of EA concentrations of 8 μ M, Fe in a test solution of pH 6.5, Tris-tartaric acid buffer concentration of 0.01M and methanol volume fraction of 80%³⁺The concentration was 1.1. mu.M and Fe²⁺The concentrations were 0.08. mu.M, 0.09. mu.M, 0.1. mu.M, 0.2. mu.M, 0.3. mu.M, 0.4. mu.M, 0.5. mu.M, 0.6. mu.M, 0.7. mu.M, 0.8. mu.M, 0.9. mu.M, 1.0. mu.M and 1.1. mu.M, respectively, and the Fe-free concentration was measured by using 357nm as the excitation wavelength, 5nm excitation slit, 5nm emission slit, 700V photomultiplier voltage²⁺Mixing Fe solutions of different concentrations for 10 times²⁺The solutions were run 3 times each and the fluorescence emission intensity changes were recorded and the results are shown in FIG. 9.

As can be seen in FIG. 9, the fluorescence emission intensity of probe EA varies with Fe²⁺Quenching by increasing concentration, and Fe²⁺When the concentration of (A) is 0.08-1.10 mu M, the fluorescence emission intensity of the probe EA and Fe²⁺In a linear relationship. The linear regression equation is obtained as F ═ 1078.43c +4297.06 (R)²0.9962), wherein F represents fluorescence emission intensity, and c represents Fe²⁺The concentration of (D) (unit: μ M). When the signal-to-noise ratio is 3, according to the formula: 3 sigma/k, the detection limit is 76nM, and the fact that tartaric acid can mask Fe is also proved³⁺And has good masking effect, and [ Fe (C)₄H₄O₆)₃]^3-The presence of (2) does not cause excessive interference to the detection result.

Example 5

This example provides EA and Fe²⁺And Fe³⁺The mixture ratio of (A) is explored.

EA and Fe²⁺And Fe³⁺The proportion of the compound (A) is studied by adopting a Job's plot method to control the compounds EA and Fe²⁺EA and Fe³⁺The total concentration of (A) is 10 mu M and compounds EA and Fe are prepared²⁺EA and Fe³⁺In a concentration ratio of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, respectively, such that Fe²⁺、Fe³⁺10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 70 wt.%, 80 wt.%, 90 wt.%, 100 wt.%, respectively, of the total concentration of the respective system. Taking the fluorescence enhancement value (F-F)₀) As ordinate, Fe²⁺、Fe³⁺The specific gravity of the total concentration is plotted on the abscissa, and the results are shown in FIG. 10 (Fe)²⁺) FIG. 11 (Fe)³⁺) As shown. From these two figures, it can be seen that for Fe²⁺In other words, at a ratio of about 0.75, F-F₀Reaching a maximum value; for Fe³⁺In other words, at a ratio of about 0.66, F-F₀A maximum value is reached. When F-F₀When the maximum value is reached, coordination is maximum, so EA and Fe²⁺Has a coordination ratio of 1:3 to Fe³⁺The coordination ratio of (A) to (B) is 1: 2.

Example 6

This example provides a Fe²⁺/Fe³⁺And (3) when the concentration ratio is more than 0.07, detecting the concentration of iron ions in tap water and Zhujiang water.

Since there is no suitable iron ion to pollute the water source, this example simulates the polluted water source to be detected by adding iron ions to tap water and Zhujiang water. The specific process is as follows:

preparing a water sample to be detected: taking tap water and Zhujiang water as two groups of basic water bodies, and adding Fe into each group of basic water bodies² ⁺、Fe³⁺Standard solution, each group of basic water is divided into Fe only²⁺Of only Fe³⁺And at the same time comprises Fe²⁺、Fe³⁺And 3 water samples to be detected. Each water sample to be tested is divided into 3 cases with different iron ion concentrations, so that the Fe in the 3 water samples to be tested²⁺/Fe³⁺The concentrations were 0.2, 0.5 and 1.0. mu.M, respectively.

Taking the above-mentioned Fe only²⁺And Fe²⁺Adding Tris-HCl buffer solution and methanol into water samples to be detected with the concentrations of 0.2, 0.5 and 1.0 mu M respectively to ensure that the concentration of the Tris-HCl buffer solution in the whole solution is 0.01M and the volume fraction of the methanol is 80 percent, and then adding Na into the water₂EA, making Na in the whole solution₂The concentration of EA was 8. mu.M. Detecting the fluorescence emission intensity of all water samples to be detected according to a linear regression equation F ═ 1099.47c +4241.78 (Fe)²⁺) Calculating to obtain Fe in water sample²⁺Assay concentration, Fe calculated as assay concentration divided by standard concentration (0.2, 0.5 and 1.0. mu.M)²⁺The results of the recovery of (A) are shown in Table 1. For Fe²⁺、Fe³⁺Coexisting solution, when addedHydroxylamine hydrochloride to Fe³⁺Reduction to Fe²⁺Then, the solution is totally Fe²⁺However, this example demonstrates that ellagic acid can be reacted with mono-Fe²⁺Fe in solution²⁺The concentration was measured and thus the results indirectly demonstrate that Fe can be detected by ellagic acid²⁺、Fe³⁺The total iron concentration in the coexisting solution and the recovery rate is 80-120%.

Taking the above-mentioned Fe only³⁺And Fe³⁺Adding Tris-HCl buffer solution and methanol into water samples to be detected with the concentrations of 0.2, 0.5 and 1.0 mu M respectively to ensure that the concentration of the Tris-HCl buffer solution in the whole solution is 0.01M and the volume fraction of the methanol is 80 percent, and then adding Na into the water₂EA, making Na in the whole solution₂The concentration of EA was 8. mu.M. Detecting the fluorescence emission intensity of all water samples to be detected according to a linear regression equation F-1080 c +4108.52 (Fe)³⁺) Calculating to obtain Fe in water sample³⁺Assay concentration, Fe calculated as assay concentration divided by standard concentration (0.2, 0.5 and 1.0. mu.M)³⁺The results of the recovery of (A) are shown in Table 1.

The above-mentioned material also contains Fe²⁺、Fe³⁺And Fe²⁺Concentrations of 0.2, 0.5 and 1.0. mu.M respectively and Fe³⁺Adding diammonium tartrate into a water sample to be detected with the concentration of 1.1 mu M to ensure that the concentration of diammonium tartrate in the whole solution is 0.01M, then adding Tris-HCl buffer solution and methanol to ensure that the concentration of the Tris-HCl buffer solution in the whole solution is 0.01M and the volume fraction of the methanol is 80%, and adding Na into the water₂EA, making Na in the whole solution₂The concentration of EA was 8. mu.M. Detecting the fluorescence emission intensity of all water samples to be detected according to a linear regression equation F ═ 1078.43c +4297.06 (Fe)²⁺Shielding Fe³⁺) Calculating to obtain Fe in water sample²⁺The detected concentration of (4) was calculated as the detected concentration divided by the standard concentration (0.2, 0.5 and 1.0. mu.M) to obtain Fe²⁺The results of the recovery of (A) are shown in Table 1.

It should be noted that when shielding Fe³⁺Of (i) Fe²⁺When the detection recovery rate is still 80-120%, the result shows that the ellagic acid can react with Fe²⁺、Fe³⁺Fe in coexisting solution²⁺Concentration detection. Since the above examples have demonstrated that Fe can be detected by ellagic acid²⁺、Fe³⁺The total iron concentration in the coexisting solution, and the recovery rate is 80% -120%, therefore, the Fe is subtracted by the total iron concentration²⁺The concentration of Fe can be further accurately obtained²⁺、Fe³⁺Fe in coexisting solution³⁺And (4) concentration.

TABLE 1

As can be seen from Table 1, the above method was used to detect Fe in tap water and Zhujiang water²⁺/Fe³⁺The recovery rate is 81.15-116.43%. In which Fe is detected alone²⁺The recovery rate is 87.34-105.46%, and Fe³⁺Between 81.15 and 112.96 percent and masks Fe³⁺Measuring Fe²⁺Of (i) Fe²⁺The recovery rate is 86.88-116.43%. Proves that the fluorescent probe ellagic acid provides high-selectivity Fe²⁺、Fe³⁺And (3) a detection method.

Example 7

This example provides a Fe²⁺/Fe³⁺A method for detecting the concentration of iron ions in Zhujiang water when the concentration ratio is less than or equal to 0.07.

Moxifloxacin p-Fe³⁺Quantitative detection of

Fluorescence scans were performed in the following experiments using 295nm as the excitation light source and 700V as the excitation voltage. Gradually dripping Fe into 2 mu M moxifloxacin aqueous solution³⁺Solution with Fe³⁺The concentration of the solution is increased (the concentration of ferric ions is 0, 0.05, 0.125, 0.25, 0.375, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75, 2.00, 2.50, 3.00, 3.75, 5.00, 7.50, 12.50, 15.00, 20.00, 25.00and 30.00 mu M in sequence from bottom to top), the fluorescence emission intensity of the solution is obviously changed, and the fluorescence intensity is changed along with the concentration of ferric ionsIs doped with Fe³⁺Gradually decreases with increasing concentration of (c). Taking the fluorescence emission intensity at the highest point of the fluorescence intensity as the ordinate, Fe³⁺The concentration is plotted on the abscissa to obtain a quadratic curve. Using Origin software to fit the quadratic curve relation between the two to obtain curve equation delta F-1868.12 × c^1/2-467.71(Fe³⁺)。

Since there is no suitable iron ion to pollute the water source, this example simulates the polluted water source to be detected by adding iron ions to the zhujiang water. The specific process is as follows:

adding Fe into Zhujiang water²⁺、Fe³⁺Standard solution of water containing Fe²⁺And Fe³⁺And is Fe²⁺Is 0.08. mu.M, Fe³⁺The concentrations of (A) and (B) are 1.2. mu.M, 3.6. mu.M and 10.8. mu.M, respectively, and the samples are used as water samples to be detected. Adding moxifloxacin to obtain a solution with the concentration of 2 mu M of moxifloxacin, then adding a Tris-HCl buffer solution to obtain a solution with the concentration of 0.01M of the Tris-HCl buffer solution, and detecting the fluorescence emission intensity of the solution to be F; adding moxifloxacin into Zhujiang water to obtain 2 mu M moxifloxacin blank solution, and detecting the fluorescence intensity of the moxifloxacin blank solution to be F₀According to F₀－F＝1868.12*c^1/2Calculating Fe in the solution by a linear regression equation of-467.71³⁺The detected concentrations c of (1.02. mu.M, 4.00. mu.M, 12.44. mu.M), Fe was calculated by dividing the detected concentrations by the standard concentrations of 1.2. mu.M, 3.6. mu.M, 10.8. mu.M³⁺The recovery rates of (A) were 85.00%, 111.11% and 115.19%, respectively. Since example 6 has demonstrated that Fe can be detected by ellagic acid²⁺、Fe³⁺The total iron concentration in the coexisting solution, and the recovery rate was 80% to 120%, so that Fe obtained in this example was subtracted from the total iron concentration³⁺The concentration of Fe can be further accurately obtained²⁺、Fe³⁺Fe in coexisting solution²⁺And (4) concentration.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. A method for detecting di/ferric ions in a water body is characterized by comprising the following steps:

taking a water sample to be detected, adding hydroxylamine hydrochloride into the water sample to ensure that Fe in the solution³⁺All reduced to Fe²⁺Adding Tris-HCl buffer solution and methanol to obtain solution I, and adding Na into the solution I₂EA to obtain solution II, and detecting fluorescence emission intensity F of solution II₁According to F₁=-1099.47c₁+4241.78 Linear regression equation for Fe in solution²⁺With Fe³⁺Wherein, F₁As intensity of fluorescence emission, c₁Is Fe²⁺With Fe³⁺(ii) total concentration of (d);

when Fe²⁺/Fe³⁺When the concentration ratio is more than 0.07, another part of water sample to be detected is taken, diammonium tartrate is added into the water sample to be detected to obtain a solution III, Tris-HCl buffer solution and methanol are added into the solution III to obtain a solution IV, and Na is added into the solution IV₂EA to obtain solution V, and detecting fluorescence emission intensity F of solution V₂According to F₂=-1078.43c₂+4297.06 Linear regression equation for Fe in solution²⁺A concentration of (b) then c₂Is Fe in the water sample to be measured²⁺C is a concentration of₁-c₂Is Fe in the water sample to be measured³⁺Wherein, F₂Is the fluorescence emission intensity;

when Fe²⁺/Fe³⁺When the concentration ratio is less than or equal to 0.07, another part of water sample to be detected is taken, moxifloxacin is added to obtain a solution VI, then a Tris-HCl buffer solution is added to the solution VI to obtain a solution VII, and the fluorescence emission intensity of the solution VII is detected to be F₃(ii) a Adding moxifloxacin into distilled water to obtain 2 μ M moxifloxacin blank solution, and detecting its fluorescence intensity to be F_0，According to F₀－F₃=1868.12 *c₃ ^1/2Calculating Fe in the solution by a linear regression equation of-467.71³⁺A concentration of (b) then c₃For water sample to be measuredFe in (1)³⁺C is a concentration of₁-c₃Is Fe in the water sample to be measured²⁺The concentration of (c);

。

2. the method for detecting di/trivalent iron ions in a water body according to claim 1, characterized in that: in the solution I in the step (1), the solution IV in the step (2) and the solution VII in the step (2), the concentration of Tris-HCl buffer solution is 0.01M.

3. The method for detecting di/trivalent iron ions in a water body according to claim 1, characterized in that: in the solution I in the step (1) and the solution IV in the step (2), the volume fraction of methanol is 80%.

4. The method for detecting di/trivalent iron ions in a water body according to claim 1, characterized in that: in the solution II in the step (1) and the solution V in the step (2), Na₂The concentration of EA was 8. mu.M.

5. The method for detecting di/trivalent iron ions in a water body according to claim 1, characterized in that: in the solution III in the step (2), the concentration of diammonium tartrate is 0.01M.

6. The method for detecting di/trivalent iron ions in a water body according to claim 1, characterized in that: in the solution VI and the moxifloxacin blank solution in the step (2), the concentration of moxifloxacin is 2 mu M.

7. The method for detecting di/trivalent iron ions in a water body according to claim 1, characterized in that: and (2) detecting the fluorescence emission intensity of the detection solution II in the step (1) and the fluorescence emission intensity of the detection solution V in the step (2) under the conditions that 357nm is used as an excitation wavelength, 5nm excitation slits, 5nm emission slits and 700V photomultiplier voltage, and recording the fluorescence emission intensity within the wavelength range of 377-650 nm.

8. The method for detecting di/trivalent iron ions in a water body according to claim 1, characterized in that: and (2) after adding the Tris-HCl buffer solution and the methanol in the step (1) and adding the Tris-HCl buffer solution and the methanol in the step (2), adjusting the pH value of the solution to be 5-7.

9. The method for detecting di/trivalent iron ions in a water body according to claim 1, characterized in that: the method for detecting the di/ferric ions in the water body is suitable for Fe²⁺Or Fe³⁺The concentration of (a) is in the range of 0.08-1.10 mu M.