Preparation method of mixed additive for detecting total arsenic and total antimony in environmental sample by atomic fluorescence method

Abstract

The invention belongs to the technical field of geological sample detection and analysis, and relates to a preparation method of a mixed additive for detecting total arsenic and total antimony in an environmental sample by an atomic fluorescence method. The preparation method comprises the following steps: adding thiourea and deionized water into a container according to a mass ratio of 1: (13-15), heating at 450-550 DEG C until the thiourea and the deionized water are completely dissolved, and rapidly stirring; then slowly adding deionized water at 8-12 DEG C while stirring; hydrochloric acid is slowly added, wherein the volume mass ratio of the hydrochloric acid to the thiourea is 10ml: 1g, and the hydrochloric acid and the thiourea are rapidly stirred while being added until the mixture is uniformly mixed; the mass ratio of the tartaric acid to the thiourea is 1: 1, and quickly stirring until the tartaric acid is dissolved; the mass ratio of the Vc ascorbic acid to the thiourea is 1: 2, and rapidly stirring until the Vc ascorbic acid is dissolved to obtain the mixed additive. The mixed additive with masking, hydrolysis resistance and acidity functions is prepared, so that the problems of low efficiency, long flow and the like in the process of measuring an environmental sample by atomic fluorescence are solved, and reagent support is provided for direct testing in a non-laboratory environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of geological sample detection and analysis, and specifically relates to a method for preparing a mixed additive for detecting total arsenic and total antimony in environmental samples by atomic fluorescence method. The present invention can be widely used in the fields of marine geology, marine minerals, marine surveys, etc., and can also be used in the fields of analysis, testing, research, teaching, etc. related to marine environmental samples in geology, mining, environmental protection, medicine, materials, chemical industry, universities, research institutes, etc. Background Art

[0002] In recent years, with the continuous deepening of geological surveys and scientific research, the demand for testing environmental samples has also been increasing. Environmental samples include solid samples such as soil sediments and marine sediments. Marine sediments are the general term for seabed sediments formed by various marine sedimentation processes. They are materials deposited on the seabed with seawater as the medium. The demand for how to quickly, efficiently and accurately test the total arsenic and total antimony in environmental samples has become increasingly prominent.

[0003] At present, when the total arsenic and total antimony in environmental samples are detected, the sample to be tested needs to be made into a digestion solution, that is, the sample to be tested is ground into powder, added with aqua regia and treated in a boiling water bath for two hours. At this time, the elements to be tested (total arsenic and / or total antimony) in the sample have completely entered the solution, and then the reducing agent (thiourea), anti-hydrolysis agent, acidity agent, masking agent (Vc solution) and other reagents must be added to the solution in sequence. However, there are situations in which the chemical and physical properties of the above-mentioned reagents conflict, repel and influence each other between the preparation principles and preparation steps. If they are mechanically prepared into a solution, their properties will change substantially and lose their original effects.

[0004] Therefore, there are two existing methods: one is to prepare the above-mentioned reducing agent, anti-hydrolysis agent, acidity agent, and masking agent four reagent solutions separately, and add these four reagent solutions one by one when using; the other is to prepare the reducing agent and the masking agent at the same time. The problem with this method is that it must be prepared at room temperature. Since thiourea has a low solubility in deionized water at room temperature, and Vc cannot be heated, it requires long-term stirring to completely dissolve. Taking the preparation of 2000mL as an example, it generally takes more than several hours, which is time-consuming. The other two reagents (anti-hydrolysis agent and acidity) have the same requirements as the first method and need to be prepared separately.

[0005] The existing methods have the following four main defects:

[0006] First, the preparation is complicated and the principles conflict with each other. Thiourea reagent is slightly soluble in cold water and easily soluble in hot water, so the preparation of this solution requires heating the solution to near boiling; the preparation of Vc solution cannot be heated and requires long-term stirring. If the temperature is slightly higher, decomposition and oxidation reactions will occur and the effect will be lost; hydrochloric acid (acidity agent) will release heat when diluted; tartaric acid (anti-hydrolysis agent) solution should be strictly controlled at room temperature during preparation. If the temperature is too high, a polymerization chemical reaction will occur to generate meta-tartaric acid. Comprehensive analysis of the above situation shows that thiourea solution, Vc solution, tartaric acid solution, and hydrochloric acid solution all need to be prepared separately. If they are added to the container together after weighing for preparation, the heated solutions will affect each other and lose their effect. If they are not heated, thiourea will form crystals and precipitate at the bottom of the container, which will also lose its effect.

[0007] Second, the preparation time is long and the process is complicated. It takes a long time to prepare the four solutions separately, which will correspondingly lengthen the test process. However, the pre-treatment time of arsenic and antimony element testing technology is not easy to be too long. Therefore, in order to solve this problem, chemical engineers are generally added and multiple people work together to complete it, resulting in a waste of human resources.

[0008] Third, there are many preparation containers, which increases the risk of contamination. Arsenic, antimony, selenium, mercury, and bismuth are generally called volatile elements in the local chemical testing industry. The main reason is that these elements are easy to volatilize during the pretreatment process. This characteristic easily leads to pollution accidents. The existing method uses separate preparation operations, which involves more utensils and more labor, increasing the risk of contamination, and thus causing errors in test results.

[0009] Fourth, it is difficult to repack, which limits the development of technology. Since arsenic and antimony are volatile elements, untreated samples are very likely to change in the process of being brought back to the laboratory from the field. However, if the samples can be pre-treated directly in the field and the content of arsenic and antimony can be stabilized in the container, the risk will be more effectively avoided. The existing technology cannot produce mixed reagents, does not have the conditions for repackaging, and cannot realize field testing, which has become one of the important bottlenecks for the development of this testing technology to non-laboratory environments.

[0010] In order to solve the above problems, the present invention starts from the principle and seeks to develop a new additive preparation method. Summary of the invention

[0011] The purpose of the present invention is to solve the above-mentioned problems existing in the prior art. A method for preparing a mixed additive for detecting total arsenic and total antimony in environmental samples by atomic fluorescence method is proposed. A multifunctional mixed additive with masking function, anti-hydrolysis function and acidity function is prepared to solve the problems of low energy, low efficiency and long process in the process of atomic fluorescence determination of various environmental samples, and provide technical support in terms of reagents for direct testing in non-laboratory environments (such as field operations at sea and in mountainous areas).

[0012] The technical solution of the present invention is:

[0013] The present invention provides a method for preparing a mixed additive for detecting total arsenic and total antimony in environmental samples by atomic fluorescence method, comprising the following steps:

[0014] (1) Thiourea and deionized water are mixed in a mass ratio of 1:(13-15) and added to a container, heated at 450-550° C. until the thiourea is completely dissolved, and then rapidly stirred for 8-10 seconds; preferably, the mass ratio of thiourea to deionized water is 1:14.

[0015] (2) slowly adding deionized water at 8 to 12° C. to the solution of step (1) while rapidly stirring;

[0016] (3) slowly adding a certain mass of hydrochloric acid to the solution of step (2), stirring rapidly while adding until the mixture is uniformly mixed, wherein the volume mass ratio of the hydrochloric acid to the thiourea is 10 ml: 1 g;

[0017] (4) Weigh a certain mass of tartaric acid, add it to the solution of step (3), and stir rapidly until dissolved, wherein the mass ratio of tartaric acid to thiourea is 1:1;

[0018] (5) Weigh a certain mass of Vc ascorbic acid in a mass ratio of Vc ascorbic acid to thiourea of ​​1:2, add the mixture to the solution of step (4), and stir rapidly until dissolved to obtain a mixed additive.

[0019] In the above preparation method, the order of adding the materials cannot be changed: including the order of adding the first added deionized water, thiourea, the second added deionized water, hydrochloric acid, tartaric acid, and Vc ascorbic acid cannot be changed and must be added according to the order in the steps.

[0020] Furthermore, the container used in step (1) is a cylindrical container, the ratio of its diameter to height is 2:5, and its volume is selected according to the amount of the mixed additive solution prepared. It should be noted that the container used in the present invention is a special container with a specified shape ratio, preferably a high-temperature cylindrical glass beaker with a diameter to height ratio of 2:5. This size is the best ratio obtained in multiple experiments and plays a key role in the preparation process of the mixed additive solution.

[0021] Furthermore, in the step (1), thiourea is added to deionized water without stirring, and the water is kept still during heating. After heating for 2 to 5 minutes until the thiourea is dissolved, heating is stopped and the water is stirred rapidly.

[0022] Furthermore, the volume ratio of the deionized water added in step (2) to the deionized water added in step (1) is 8:7;

[0023] The deionized water should be added evenly and slowly, and stirred rapidly during the addition to prevent the precipitation of thiourea.

[0024] Furthermore, in step (3), hydrochloric acid is slowly added while being rapidly stirred until the solution is uniformly mixed and the solution temperature is within room temperature.

[0025] The present invention also provides a mixed additive prepared by any of the above-mentioned preparation methods and used for detecting total arsenic and total antimony in environmental samples by atomic fluorescence method.

[0026] The mixed additive can be used as an additive reagent before testing environmental samples such as environmental water bodies (rivers, lakes and seas), silicate (soil, marine sediments) aqua regia digestion solution, and aerosol digestion solution.

[0027] The mixed additive can simultaneously have the effects of reducing, masking, anti-hydrolysis and acidity enhancement during use.

[0028] The present invention further provides the use of the mixed additive prepared by any of the preparation methods described above in detecting total arsenic and total antimony in environmental samples by atomic fluorescence spectrometry.

[0029] Furthermore, the mixed additive can be used for detection under laboratory conditions or for detection under non-laboratory conditions.

[0030] Furthermore, when used in a laboratory environment, the mixed additive is quantitatively added to the sample to be tested, and the sample is shaken well before being tested on a machine;

[0031] When used in a non-laboratory environment, the mixed additives are pre-packed into disposable plastic sealable bags, and after sampling, the required amount of the mixed additives is added to the sample.

[0032] Beneficial effects of the present invention:

[0033] (1) The present invention starts from the preparation principle, formulates a new preparation process, strictly formulates the preparation details, and prepares the reducing agent, masking agent, anti-hydrolysis agent, and strong acid agent into a mixed reagent in proportion, and the properties and effects remain unchanged; compared with a single solution, the mixed reagent has the effects of reducing, masking, strong acid, and anti-hydrolysis at the same time, has more comprehensive functions, good effects, and greatly simplifies the preparation process.

[0034] (2) The preparation method of the present invention has an easy-to-operate process, simple containers and tools, and can save labor, thereby eliminating the pollution problem introduced by multiple vessels and tools, and eliminating the test error problem introduced by complex personnel.

[0035] (3) The preparation method of the mixed additive can obtain a mixed reagent with good performance in four aspects: reduction effect, masking (anti-interference) effect, strong acidity effect, and anti-hydrolysis effect. If necessary, the mixed reagent can be packaged into reagent packages according to dosage, marked with the preparation date and shelf life, and used in non-laboratory environments; therefore, whether in the laboratory or in the field, it can meet the requirements of rapid processing, improve efficiency, and be more conducive to large-scale testing.

[0036] (4) The method of the present invention is a new mixed additive preparation method in the atomic fluorescence detection technology of total arsenic and total antimony, which solves the problem of formula preparation of mixed reagents and fills the problem of field testing and laboratory efficient testing in atomic fluorescence testing technology. The mixed additive has been tested and verified in a large number of samples in a professional marine geological experimental test room, and the effect is satisfactory, which greatly promotes the progress of total arsenic and total antimony testing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Three beakers of different sizes are provided for Test Example 1 of the present invention; among them, a is an ordinary beaker, b is a beaker of special size of the present invention, and c is a special beaker with increased size ratio and different size from the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] This embodiment provides a method for preparing a mixed additive for detecting total arsenic and total antimony in environmental samples by atomic fluorescence spectrometry. Taking the preparation of 2000 mL of mixed reagent as an example, a high-temperature glass beaker with a diameter of 10 cm and a height of 25 cm is used as a container for preparing the solution. The method includes the following steps:

[0041] Before preparation, take out the reagent bottle and place 800 mL of deionized water in a refrigerator at a constant temperature of 10°C for later use.

[0042] (1) Add 700 mL of deionized water to a specific beaker (prepared with a 2000 mL special beaker), weigh 50 g of analytical pure thiourea reagent and add it to the beaker, and heat it at 500°C in a small electric furnace. Note that after pouring thiourea into the beaker, the solution in the beaker must be kept in a static state until the beaker is placed on the small electric furnace. During the heating process, no external operations such as shaking or stirring the solution in the beaker should be performed. At the same time, observe the bottom of the beaker at any time. After heating for about 3 minutes, when the thiourea particles at the bottom of the beaker are evaporating and completely dissolved, remove the beaker immediately and stir it quickly for 10 seconds with a long glass rod.

[0043] (2) Take out the reagent bottle from the refrigerator and slowly add all the 800 mL of reserved deionized water into the beaker of step (1). To prevent the precipitation of thiourea, the addition process should be uniform and slow. The addition time must be controlled to be more than 2 minutes. Stir quickly with a long glass rod while adding. When the addition is completed, the solution temperature is slightly below room temperature.

[0044] (3) Slowly add 500 mL of high-grade pure hydrochloric acid over a period of more than 1 minute, stirring rapidly with a glass rod while adding to mix evenly. At this point, the solution temperature is within room temperature.

[0045] (4) Weigh 50 g of solid tartaric acid reagent, add it to this special container, and stir quickly with a glass rod to dissolve it.

[0046] (5) Weigh 25 g of Vc ascorbic acid solid reagent, add it to the special container, stir quickly to dissolve, and the mixed additive preparation is complete.

[0047] The method of using the prepared mixed additive is as follows:

[0048] When used in a laboratory environment, add the solution directly in a quantitative amount using a bottle-top pipette, shake well, and test on the machine.

[0049] For example: if the solution to be tested is 2 mL, then it is appropriate to add 8 mL of mixed additives.

[0050] Shelf life of mixed additives: The mixed additives should not be kept in the laboratory for more than 24 hours (one day) from the time they are prepared to the time they are added to the test solution.

[0051] When used in a non-laboratory environment, the mixed additives can be placed in a disposable plastic sealable bag (with a silver reflective shiny surface inside) in advance. The packaging volume can be designed according to the test needs. For example, if the water to be tested is 2mL, 8mL of mixed reagent per bag is appropriate.

[0052] In an outdoor environment, take 2 mL of environmental water, add 8 mL of additive, and mix well.

[0053] Shelf life: After bagging, it should not be used for more than 72 hours (three days) outside the laboratory environment.

[0054] Example 2

[0055] This embodiment provides a method for preparing a mixed additive for detecting total arsenic and total antimony in environmental samples by atomic fluorescence method, which also uses a high-temperature cylindrical glass beaker with a diameter-to-height ratio of 2:5. The preparation method includes the following steps:

[0056] Before preparation, take out the reagent bottle and place 1600 ml of deionized water in a refrigerator at a constant temperature of 8°C for later use.

[0057] (1) Add 1400 mL of deionized water to a specific beaker, weigh 100 g of analytical grade thiourea reagent and add it to the beaker, and heat it in a small electric furnace at 550°C. Note that after pouring thiourea into the beaker, the solution in the beaker must be kept in a static state until the beaker is placed on the small electric furnace. During the heating process, no external operations such as shaking or stirring the solution in the beaker should be performed. At the same time, observe the bottom of the beaker at any time. After heating for 5 minutes, when the thiourea particles at the bottom of the beaker are evaporating and completely dissolved, remove the beaker immediately and stir it quickly for 8 seconds with a long glass rod.

[0058] (2) Take out the reagent bottle from the refrigerator and slowly add all the 1600 mL of spare deionized water into the beaker of step (1). To prevent the precipitation of thiourea, the addition process should be uniform and slow. The addition time must be controlled to be more than 2 minutes. Stir quickly with a long glass rod while adding. When the addition is completed, the solution temperature is slightly below room temperature.

[0059] (3) Slowly add 1000 mL of high-grade pure hydrochloric acid over a period of more than 1 minute, stirring rapidly with a glass rod while adding to mix evenly. At this point, the solution temperature is within room temperature.

[0060] (4) Weigh 100 g of solid tartaric acid reagent, add it to this special container, and stir quickly with a glass rod to dissolve it.

[0061] (5) Weigh 50 g of Vc ascorbic acid solid reagent, add it to the special container, stir quickly to dissolve, and the mixed additive preparation is complete.

[0062] Example 3

[0063] This embodiment provides a method for preparing a mixed additive for detecting total arsenic and total antimony in environmental samples by atomic fluorescence method, which also uses a high-temperature cylindrical glass beaker with a diameter-to-height ratio of 2:5. The preparation method includes the following steps:

[0064] Before preparation, take out the reagent bottle and place 400 mL of deionized water in a refrigerator at a constant temperature of 12°C for later use.

[0065] (1) Add 350 mL of deionized water to a specific beaker, weigh 24 g of analytical grade thiourea reagent and add it to the beaker, and heat it at 450°C in a small electric furnace. Note that after pouring thiourea into the beaker, the solution in the beaker must be kept in a static state until the beaker is placed on the small electric furnace. During the heating process, no external operations such as shaking or stirring the solution in the beaker should be performed. At the same time, observe the bottom of the beaker at any time. After heating for 2 minutes, when the thiourea particles at the bottom of the beaker are evaporating and completely dissolved, remove the beaker immediately and stir it quickly for 9 seconds with a long glass rod.

[0066] (2) Take out the reagent bottle from the refrigerator and slowly add all the 400 mL of reserved deionized water into the beaker of step (1). To prevent the precipitation of thiourea, the addition process should be uniform and slow. The addition time must be controlled to be more than 2 minutes. Stir quickly with a long glass rod while adding. When the addition is completed, the solution temperature is slightly below room temperature.

[0067] (3) Slowly add 240 mL of high-grade pure hydrochloric acid over a period of more than 1 minute, stirring rapidly with a glass rod while adding to mix evenly. At this point, the solution temperature is within room temperature.

[0068] (4) Weigh 24 g of solid tartaric acid reagent, add it to this special container, and stir quickly with a glass rod to dissolve it.

[0069] (5) Weigh 12 g of Vc ascorbic acid solid reagent, add it to the special container, stir quickly to dissolve, and the mixed additive preparation is complete.

[0070] Test Example 1

[0071] like Figure 1 As shown, this experiment provides three beakers of different sizes, which are heated and dissolved in a small electric furnace to dissolve the thiourea reagent, and then a comparative analysis is performed.

[0072] The first is a regular size beaker (see Figure 1 In a), the solid line in the picture is the solution surface, and the dotted line is the insulation line during the heating process. After 700 mL of deionized water is added to the ordinary beaker, the volume is spread flat on the bottom of the beaker, the contact area with the small electric furnace is large, the heating area is large, and the liquid surface height is low. During the heating process, without stirring, the heat is quickly conducted upward in the solution. When the thiourea is completely dissolved, the temperature of the upper solution also increases. The temperature difference between the upper and lower layers of the solution is small. If it is stirred again, the overall temperature of the solution in the beaker is high, which is not conducive to subsequent operations.

[0073] The second is a beaker of special size according to the present invention (see Figure 1b), that is, the ratio of diameter to height is 2:5. Without stirring, the heat conduction in the solution becomes slower. When the thiourea at the bottom is completely dissolved, the upper solution is still slightly higher than room temperature, and the temperature difference between the upper and lower layers of the solution is large. When the thiourea is completely dissolved and the beaker is removed for stirring, a solution with an ideal temperature can be obtained, which is conducive to subsequent operations.

[0074] The third type of special beaker (see Figure 1 c) is different from the present invention in that the size ratio is increased, the temperature difference between the upper and lower parts of the solution is larger after the thiourea is dissolved, and the temperature is lower after stirring. However, since the bottom size of the beaker is too small, the volume of water that the thiourea reagent contacts when it is dissolved is also smaller, and heating takes longer, which is not conducive to improving efficiency, and is therefore not suitable.

[0075] After many experiments, it was found that when the beaker size ratio is controlled at a diameter to height ratio of 2:5, thiourea solution with suitable temperature can be obtained and rapid operation can be achieved.

[0076] Test Example 2

[0077] The mixed additive prepared by the present invention was used to conduct a national primary standard material test experiment on marine sediments and soils, and the data are shown in Table 1.

[0078] Table 1 Data statistics

[0079]

[0080]

[0081] Table 2 Recommended value comparison table

[0082]

[0083]

[0084] It can be seen from the data in Table 1 and Table 2 that, for national primary standard materials of marine sediments and soils with different contents, the mixed additive prepared by the present invention is used to carry out multiple batches of determination to obtain the average value, and the test values ​​are consistent with the recommended values, and the standard deviations are all less than 3%, which meets the quality requirements, further illustrating the feasibility and accuracy of the formula of the present invention.

[0085] The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments, or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, modification, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a mixed additive for detecting total arsenic and total antimony in environmental samples by atomic fluorescence spectrometry, characterized in that: The following steps are involved: (1) Mix thiourea and deionized water in a mass ratio of 1:(13-15) and add them into a container, heat at 450-550°C until the thiourea is completely dissolved, and stir rapidly for 8-10 seconds; (2) slowly adding deionized water at 8 to 12° C. to the solution of step (1) while rapidly stirring; (3) slowly adding a certain mass of hydrochloric acid to the solution of step (2), stirring rapidly while adding until the mixture is uniformly mixed, wherein the volume mass ratio of the hydrochloric acid to the thiourea is 10 ml: 1 g; (4) Weigh a certain mass of tartaric acid, add it to the solution of step (3), and stir rapidly until dissolved, wherein the mass ratio of tartaric acid to thiourea is 1:1; (5) Weigh a certain mass of Vc ascorbic acid in a mass ratio of Vc ascorbic acid to thiourea of ​​1:2, add the mixture to the solution of step (4), and stir rapidly until dissolved to obtain a mixed additive.

2. The preparation method according to claim 1, characterized in that: The container used in step (1) is a cylindrical container, the ratio of its diameter to its height is 2:5, and its volume is selected according to the amount of the prepared mixed additive solution.

3. The preparation method according to claim 1, characterized in that: In the step (1), thiourea is added to deionized water without stirring. The water is kept still during heating. After heating for 2 to 5 minutes until the thiourea is dissolved, heating is stopped and the water is stirred rapidly.

4. The preparation method according to claim 1, characterized in that: The volume ratio of the deionized water added in step (2) to the deionized water added in step (1) is 8:7; The deionized water should be added evenly and slowly, and stirred rapidly during the addition to prevent the precipitation of thiourea.

5. The preparation method according to claim 1, characterized in that: In the step (3), hydrochloric acid is slowly added while stirring rapidly until the solution is uniformly mixed and the solution temperature is within room temperature.

6. A mixed additive for detecting total arsenic and total antimony in environmental samples by atomic fluorescence method, prepared according to the preparation method according to any one of claims 1 to 5.

7. Use of the mixed additive prepared by the preparation method according to any one of claims 1 to 5 in detecting total arsenic and total antimony in environmental samples by atomic fluorescence spectrometry.

8. The use according to claim 7, characterized in that: The mixed additive can be used for detection under laboratory conditions or for detection under non-laboratory conditions.

9. The use according to claim 8, characterized in that: When used in a laboratory environment, add a quantitative amount of the mixed additive to the sample to be tested, shake well, and then test on the machine; When used in a non-laboratory environment, the mixed additives are pre-packed into disposable plastic sealable bags, and after sampling, the required amount of the mixed additives is added to the sample.

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