CN110763776A - LC-HG-AFS detection method of monothioarsenate - Google Patents

Abstract

The invention discloses an LC-HG-AFS detection method of mono-thioarsenate, which comprises the following steps: preparing a test solution containing a sample to be tested; testing the test solution by adopting an LC-HG-AFS combined technology; calculating the mass concentration of the thioarsenate according to the working curve of the thioarsenate, wherein the working curve of the thioarsenate is established by the following method: preparing a thioarsenate sample, measuring the total arsenic mass concentration of the thioarsenate sample, and respectively measuring the mass concentration of arsenite and the mass concentration of arsenate in the thioarsenate sample by adopting an external standard method to establish a working curve of the thioarsenate. The method has the beneficial effect of providing detection technical support for researching the behavior characteristics of the monothioarsenate in the underground water.

Description

LC-HG-AFS detection method of monothioarsenate

technical field

The invention relates to the technical field of environmental detection. More specifically, the present invention relates to a LC-HG-AFS detection method of monothioarsenate.

Background technique

Arsenic pollution in groundwater is one of the current environmental hotspots, and long-term human intake can lead to chronic arsenic poisoning. In the iron-rich and sulfur-rich environment, in addition to the common arsenate and arsenite, the presence of thioarsenate is often detected, so speciation separation is required. Speciation separation mainly includes ion chromatography (IC), liquid chromatography (LC), anion exchange chromatography (AEC) and capillary electrophoresis (CE). Among them, the most widely used method is to use IC for morphological separation and then ICP-MS detection, but the test cost is high. As a newly discovered form of arsenic, thioarsenate needs a more convenient and economical detection method to directly determine the concentration of thioarsenate in the water environment.

SUMMARY OF THE INVENTION

An object of the present invention is to solve at least the above-mentioned problems and to provide at least the advantages which will be explained later.

Another object of the present invention is to provide a LC-HG-AFS detection method for monothioarsenate, which provides detection technical support for studying the behavior characteristics of monothioarsenate in groundwater.

In order to achieve these objects and other advantages according to the present invention, a kind of LC-HG-AFS detection method of monothioarsenate is provided, comprising the following steps:

Step 1. Configure the test solution containing the sample to be tested;

Step 2, using LC-HG-AFS combined technology to test the test solution;

Step 3. Calculate the mass concentration of the monothioarsenate according to the working curve of the monothioarsenate, wherein the method for establishing the working curve of the monothioarsenate is: configure a monothioarsenate sample, The total arsenic mass concentration was measured, denoted as ρ _{total arsenic} , and the external standard method was used to measure the mass concentration of arsenite and arsenate in the monothioarsenate sample, respectively, denoted as ρ _arsenite , ρ _arsenate , the calculation method of the mass concentration of monothioarsenate in a thioarsenate sample is recorded as ρ _{-thioarsenate} = ρ _{total arsenic} - ρ _arsenite - ρ _arsenate , and the working curve of monothioarsenate is established according to the injection amount and the mass concentration of monothioarsenate corresponding to the injection amount.

Preferably, the mass concentration of arsenite is calculated according to the standard curve of arsenite, and the mass concentration of arsenite is calculated according to the standard curve of arsenite.

Preferably, it also includes: step 4, verifying the working curve of monothioarsenate, specifically: configuring samples of monothioarsenate with different concentrations from step 3 for testing, and using the monothioarsenate sample in step 3 for testing The working curve of arsenate calculates the mass concentration of monothioarsenate, and calculates the standard deviation of monothioarsenate samples with different concentrations.

Preferably, the mobile phase of the LC-HG-AFS combined technology is a phosphate buffer solution, and the phosphate buffer solution is a diammonium hydrogen phosphate solution.

Preferably, the flow rate of the high pressure liquid pump of the LC-HG-AFS combined technology is 1.0-1.2 mL/min, and the chromatographic column is a PRP-X100 anion exchange chromatographic column.

Preferably, in the LC-HG-AFS combined technology, the negative high pressure of the atomic fluorescence spectrum is 270-280 V, the carrier gas flow is 400-450 mL/min, the shielding gas flow is 600-650 mL/min, and the peristaltic pump rotational speed is 400-450 mL/min. 65～80r/min, the total current of arsenic lamp is 80～85mA, and the auxiliary current is 35～40mA.

Preferably, in the LC-HG-AFS combined technology, the carrier current for hydride generation conditions is 6-8% hydrochloric acid solution, and the reducing agent is 2-3% potassium borohydride and 0.3-0.4% hydroxide Potassium solution.

The invention at least includes the following beneficial effects: the invention adopts the LC-HG-AFS combined technology to detect the concentration of monothioarsenate in the water environment, the sample dosage is small, the solution preparation is simple, and the requirement for an anion exchange column is low. , do not need to use an alkaline solution for gradient elution; the arsenic species in the test solution can be completely eluted and separated, and the total arsenic content loss is small; the detection method of monothioarsenate LC-HG-AFS is used to study its Behavioral characteristics in groundwater provide technical support for detection.

Other advantages, objects, and features of the present invention will appear in part from the description that follows, and in part will be appreciated by those skilled in the art from the study and practice of the invention.

Description of drawings

Fig. 1 is the LC-HG-AFS structural representation in the embodiment of the present invention;

2 is a schematic diagram of an arsenic form elution device in an embodiment of the present invention;

3 is a schematic diagram of the standard curve of arsenite and the standard curve of arsenate in the embodiment of the present invention;

Fig. 4 is the LC-HG-AFS spectrogram of No. 1 sample in the embodiment of the present invention;

Fig. 5 is the working curve schematic diagram of the monothioarsenate of No. 1 sample in the embodiment of the present invention;

Fig. 6 is the working curve schematic diagram of the monothioarsenate of No. 2 sample in the embodiment of the present invention;

7 is a schematic diagram showing the comparison of the working curves of No. 1 and No. 2 monothioarsenate in the embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the embodiments, so that those skilled in the art can implement according to the description.

It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial sources unless otherwise specified.

The LC-HG-AFS detection method of monothioarsenate includes the following steps:

LC-HG-AFS condition parameter settings are shown in Table 1;

Table 1

(1) LC-HG-AFS combined technique to establish arsenite standard curve and arsenate standard curve;

Arsenite As(III) standard solution and arsenate As(V) standard solution were prepared with concentrations of 20, 40, 60, 80 and 100 μg/L, respectively, and the injection volumes were 10, 20, 30, 40, 50 μL, and the measured results are shown in Table 2. The standard curve was prepared by external standard calibration. The standard curve is shown in Figure 3. The standard curve of arsenite is: S=7133.6C-9770.2, R ² =0.9995; the standard curve of arsenite is: S=5301.7C- 2128.6, R ² =0.9998.

Table 2 Standard curve gradient values

(2) LC-HG-AFS combined technique to establish the working curve of monothioarsenate;

Specifically: configure No. 1 sample, use No. 1 sample to construct a working curve of monothioarsenate, No. 1 sample contains 355 μg/L of sodium monothioarsenate, dilute No. 1 sample 10 times, use atomic fluorescence The total arsenic concentration was measured to be 40.5865 μg/L. LC-HG-AFS detection, the injection volume was set to 10, 30, 40, 50 and 100 μL, the peak time of arsenite was about 2 to 3 minutes, and the peak time of monothioarsenate was about 18 to 22 minutes. As shown in Figure 4, the test results are shown in Table 3. The arsenite concentration was calibrated using the arsenite standard curve, and when the injection volume was 10 μL, the arsenite concentration was 3.7541 μg/L. The peak areas of monothioarsenate measured with different injection volumes had good correlation, and the linear correlation coefficient R ² value was greater than 99.9%. Assuming that the concentration of monothioarsenate is a when the injection volume is 10 μL, when the injection volume is 30, 40, 50 and 100 μL, the concentrations of monothioarsenate are 3a, 4a, 5a and 10a, respectively, where a Represents the value as the total arsenic concentration measured by atomic fluorescence minus the arsenite and arsenate concentrations measured by LC-HG-AFS.

Table 3 Test No. 1 sample by external standard method

Note: When injecting 100μL, the peak of As(V) can be seen, and the quantitative concentration is 13.0435μg/L.

The content of arsenate in the sample was less, and no obvious peak was detected when 10, 30, 40, and 50 μL were injected. When the injection volume was 100 μL, the arsenate concentration measured by the external standard method was 13.0435 μg/L, and when the injection volume was 10 μL, the concentration was recorded as 1.3044 μg/L.

Using the formula ρ _{-thioarsenate} = ρ _{total arsenic} -ρ _arsenite -ρ _arsenate , when the injection volume is 10 μL, the concentration of monothioarsenate is a=35.528 μg/L. Since the injection volume is proportional to the measured monothioarsenate concentration, the corresponding thioarsenite concentrations are 35.528, 106.584, 142.112, 177.640 and 355.280 μg/L.

Using the injection volume of 10, 30, 40, 50 and 100 μL as the gradient, the external standard method was used to establish a monothioarsenate working curve. The external standard calibration results are shown in Table 4. In Table 4, monothioarsenate is referred to as monothioarsenate. generation. The minimum concentration of monothioarsenate detected is 35.53 μg/L, and the working curve of monothioarsenate is shown in Figure 5. Arsenite working curve: _No. S1=6962.0C- ^5764.2 , R2=0.9993; working curve of monothioarsenate: _No. S1=3264.0C ^- 18940, R2=0.9996.

Table 4 External Standard Calibration Table - Sample No. 1

Configure the No. 2 sample and use the No. 2 sample to construct the working curve of sodium thioarsenate. The No. 2 sample contains 360 μg/L of sodium monothioarsenate. The No. 2 sample is diluted 10 times, and the total arsenic is measured by atomic fluorescence. The concentration was 41.4749 μg/L. For LC-HG-AFS detection, the injection volumes were 30, 40, 50 and 100 μL, and the test results are shown in Table 5. The arsenite concentration was calibrated by the external standard method, and the average concentration was 3.5072 μg/L when the injection volume was 10 μL. There was a good correlation between different injection volumes and the measured monothioarsenate peak areas, and the linear correlation coefficient R ² value was greater than 99.9%. Assuming that the monothioarsenate concentration is b when the injection volume is 10 μL, the monothioarsenate concentrations are 3b, 4b, 5b and 10b when the injection volume is 30, 40, 50 and 100 μL, respectively.

Table 5 Test sample No. 2 by external standard method

Note: When injecting 100μL, the peak of As(Ⅴ) can be seen, and the quantitative concentration is 15.3277μg/L.

The working curve of sample No. 2 was constructed in the same way. The external standard calibration results are shown in Table 6. In Table 6, monothioarsenate is abbreviated as monothio, and the standard curve is shown in Figure 6. Arsenite working curve: _{No. S 2} = 6874.5C-4043.0, R ² =0.9992; working curve of monothioarsenate: _{No. S 2} = 3166.5C-2773.4, R ² =0.9999.

Table 6 External Standard Calibration Table - Sample No. 2

(3) Verify the working curves of No. 1 and No. 2 samples

The arsenite working curve established by sample No. 1 is: S _{No. 1} = 6962.0C-5764.2, R ² =0.9993; the arsenite working curve established by sample No. 2 is: S _{No. 2} = 6874.5C-4043.0, R ² = 0.9992; the arsenite standard curve of the standard material is: S = 7133.6C-9770.2, R ² =0.9995. The working curve of monothioarsenate established by sample No. 1 is: S _{No. 1} = 3264.0C-18940 , R ² =0.9996; the working curve of monothioarsenate established by sample No. 2 is: S _{No. 2} = 3166.5C-2773.4, R ² =0.9999. Monothioarsenate established by sample No. 1 and No. 2 The working curve is relatively close, as shown in Figure 7.

Using the working curve established by sample No. 1 to measure samples No. 2, No. 3 and No. 4, the sample No. 3 containing sodium monothioarsenate was 455 μg/L, and the sample No. 4 containing sodium monothioarsenate was 360 μg/L L, the injection volume was 100 μL, and the results are shown in Table 7. In Table 7, monothioarsenate is abbreviated as monothio. The arsenite concentration measured with the working curve of sample No. 1 and the measurement results of the arsenite standard curve were very close, with relative standard deviations of 0.44%, 1.82% and 1.17%, respectively. The measured concentration of monothioarsenate was also close to the theoretical value, with the relative standard deviations of 1.20%, 2.33% and 4.41%, respectively.

Similarly, samples No. 1, No. 3 and No. 4 were measured with the working curve established by sample No. 2, and the injection volume was 100 μL. The results are shown in Table 7. The relative standard deviations of the arsenite concentration measured by the working curve of sample No. 2 and the measurement results of the standard curve of arsenite were 0.79%, 2.44% and 1.80%, respectively; the measured monothioarsenic acid The relative standard deviations of the salt concentration and theoretical values were 1.71%, 3.71% and 5.58%, respectively.

From the measurement results of the No. 1 curve and No. 2 curve, it can be concluded that the measured values of the two working curves are close to the theoretical values, and the calibration result of the No. 1 working curve is better than that of the No. 2 working curve.

Table 7 LC-HG-AFS test results-3 and 4 samples

(4) Detection limit determination

Select 5 curves that are not measured on the same day, and calculate the noise average. Taking 3 times the signal-to-noise ratio as the detection limit, the detection limit was 33.03 μg/L by continuously diluting the sample.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the application listed in the description and the embodiment, and it can be applied to various fields suitable for the present invention. For those skilled in the art, it can be easily Therefore, the invention is not limited to the specific details and embodiments shown and described herein without departing from the general concept defined by the appended claims and the scope of equivalents.

Claims (7)

1. An LC-HG-AFS detection method of thioarsenate is characterized by comprising the following steps:

step 1, preparing a test solution containing a sample to be tested;

step 2, testing the test solution by adopting an LC-HG-AFS combined technology;

step 3, calculating the mass concentration of the monothioarsenate according to the working curve of the monothioarsenate, wherein the establishing method of the working curve of the monothioarsenate comprises the following steps: preparing a thioarsenate sample, measuring the total arsenic mass concentration and recording as rho_{Total arsenic}Respectively measuring the mass concentration of arsenite and the mass concentration of arsenate in a thioarsenate sample by adopting an external standard method, and respectively recording as rho_{Arsenite salt}、ρ_{Arsenate salt}The calculation method of the mass concentration of the monothioarsenate in the monothioarsenate sample is recorded as rho_{Monothioarsenate}＝ρ_{Total arsenic}-ρ_{Arsenite salt}-ρ_{Arsenate salt}And establishing a working curve of the thioarsenate according to the sample volume and the mass concentration of the thioarsenate corresponding to the sample volume.

2. The LC-HG-AFS method of claim 1, wherein the concentration of arsenite is calculated from a standard curve of arsenite, and the concentration of arsenate is calculated from a standard curve of arsenate.

3. The LC-HG-AFS assay of monothioarsenate according to claim 1, further comprising: step 4, verifying a working curve of the monothioarsenate, which specifically comprises the following steps: and (3) configuring monothioarsenate samples with different concentrations in the step (3) for testing, calculating the mass concentration of monothioarsenate by using the working curve of monothioarsenate in the step (3), and calculating the standard deviation of the monothioarsenate samples with different concentrations.

4. The method for LC-HG-AFS detection of mono-thio-arsenate according to claim 1, wherein the mobile phase of the LC-HG-AFS combined technology is phosphate buffer solution, and the phosphate buffer solution is diammonium phosphate solution.

5. The LC-HG-AFS detection method of mono-thio-arsenate according to claim 1, wherein the high-pressure liquid pump flow rate of the LC-HG-AFS combined technology is 1.0-1.2 mL/min, and the chromatographic column is a PRP-X100 anion exchange chromatographic column.

6. The LC-HG-AFS detection method of mono-thio-arsenate according to claim 1, wherein in the LC-HG-AFS combined technology, the negative high voltage of the atomic fluorescence spectrum is 270-280V, the carrier gas flow is 400-450 mL/min, the shielding gas flow is 600-650 mL/min, the rotation speed of a peristaltic pump is 65-80 r/min, the total current of the arsenic lamp is 80-85 mA, and the auxiliary current is 35-40 mA.

7. The LC-HG-AFS detection method of mono-thio arsenate according to claim 1, wherein the carrier current of the hydride generation condition in the LC-HG-AFS combined technology is 6-8% hydrochloric acid solution, and the reducing agent is 2-3% potassium borohydride and 0.3-0.4% potassium hydroxide solution.

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