CN103163119A - Method for measuring arsenic content of environmental samples - Google Patents

Abstract

The invention discloses a method for measuring the arsenic content of environmental samples, which is used for measuring the arsenic content of environmental samples by using a high-pressure digestion ICP-AES (inductively coupled plasma-atomic emission spectrometry) method. In the method, arsenic samples are subjected to high-pressure digestion firstly, and after a certain amount of an acid solution is added, the digestion is performed in a high-temperature and high-pressure digestion tank, so that arsenic can be dissolved effectively. Then, the arsenic content is measured by using an ICP-AES spectrometer. The detection limit of the method is between 0.06 and 1.5 mu g/kg, therefore, the method is small in matrix interference, and can satisfy the needs of production and living.

Description

Detection method of arsenic content in environmental samples

technical field

The invention relates to a method for detecting arsenic content in environmental samples, in particular to a method for determining the content of arsenic in environmental samples by high-pressure digestion ICP-AES.

Background technique

In recent years, morphological analysis has received widespread attention and developed rapidly. Environmental chemists, nutritionists, toxicologists, and geochemists all agree on the fact that the total concentration of an element is not only insufficient to evaluate its toxicity, beneficial effect, and biological effectiveness, but may even be misleading. The toxicity, bioavailability, and migration and release activity of trace elements in the environment are closely related to their occurrence state. The properties of elements in different forms vary greatly, which determines their behavior and fate in the environment. The impact of trace elements on the environment and ecosystem can be reliably evaluated only by determining the forms of elements present in specific samples. Generally, organic compounds of the same metal elements are much more toxic than the corresponding inorganic forms (except for organic arsenic). Due to their hydrophobic and lipophilic characteristics, they can enter the biological cycle and enter the human body through the enrichment of the food chain. Serious hazard to health. Alkyl compounds such as Hg, Sn, Pb are far more toxic than their inorganic forms. However, the toxicity of inorganic arsenic is higher than that of organic arsenic, and the toxicity of As(Ⅲ) in inorganic arsenic is much higher than that of As(Ⅴ). Another example is that Cr(Ⅲ) is an essential element for the normal metabolism of the human body, while Cr(Ⅵ) has high solubility and high activity, which is harmful to the heart, kidney and carcinogenic. Therefore, it is necessary to distinguish the chemical form of the elements.

The common determination method of arsenic content is mainly atomic fluorescence spectroscopy, which is a highly specific and mature determination method, and has been applied to the detection of arsenic content in various industries. However, this detection technology is rarely used in foreign countries, but inductively coupled plasma atomic emission spectrometry (ICP-AES). Inductively coupled plasma atomic emission technology has been widely used in various industries due to its high sensitivity, high accuracy, and simultaneous determination of multiple elements. It has developed rapidly in the field of elemental analysis and has gradually replaced atomic absorption spectroscopy (AAS ), atomic fluorescence spectroscopy (AFS) and ultraviolet spectroscopy (UV) and other traditional element analysis techniques have become the main detection techniques. In order to be in line with international detection technology, the present invention uses inductively coupled plasma atomic emission technology to measure the content of As in environmental samples.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a high-pressure digestion ICP-AES method for determining the arsenic content in environmental samples with low detection limit, fast and accurate detection.

Technical problem of the present invention is realized through the following technical solutions:

A high-pressure digestion ICP-MS method for determining arsenic content in environmental samples.

The steps of the As element content in the described ICP-AES method determination sample digestion solution are as follows:

(1) Weigh 0.2 g ~ 0.6 g of environmental samples and place them in a high-pressure digestion tank with a capacity of 100 mL, add 60% potassium permanganate solution and let it stand for 10 minutes, then add 10-20 mL of 90% nitric acid and 20% peroxide Hydrogen 2 ~ 5mL to make the sample liquid, then put the high pressure digestion tank containing the sample liquid into the blast drying oven; open the program control system, set the blast drying oven to heat up to 200 ℃ ~ 205 ℃, constant temperature time 5 ~ After 10 hours, turn off the power and let it cool naturally; place the sample liquid for ventilation until the sample liquid is clear, then transfer it to a 50mL plastic volumetric flask, and dilute it to 25mL with ultrapure water to obtain a sample digestion solution; in another 100mL high-pressure digestion tank Directly add 60% potassium permanganate solution and let it stand for 10 minutes, then add 10-20mL of 90% nitric acid and 2-5mL of 20% hydrogen peroxide to make sample liquid, and then put the sample liquid into the high-pressure digestion tank In the blast drying oven; open the program control system, set the temperature of the blast drying oven to 200 ° C ~ 205 ° C, turn off the power after a constant temperature of 5 ~ 10 hours, and cool naturally; place the sample liquid for ventilation until the sample liquid is clear, and then Transfer to a 50mL plastic volumetric flask, and dilute to 25mL with ultrapure water to obtain a blank digestion solution;

(2) According to the sample digestion solution obtained in step (1), use an inductively coupled plasma spectrometer, that is, an ICP-AES instrument to measure the spectral intensity of the As element contained in the sample digestion solution at 193.696nm, and record the As intensity value;

(3) Configure the standard working solution: Weigh the As standard stock solution with a concentration of 2.0mg/mL respectively, take out 100uL of the standard stock solution and place it in a 100mL volumetric flask, add 60% potassium permanganate solution, and use a concentration of 7% The nitric acid solution was diluted into a standard solution mother solution with a concentration of 1.0mg/L, and then the standard solution mother solutions of 0uL, 10uL, 20uL, 50uL, 100uL and 200uL were taken out respectively and placed in a 10mL volumetric flask, respectively Diluted into a standard working solution, the obtained standard working solutions of 0uL, 10uL, 20uL, 50uL, 100uL, and 200uL correspond to the contents of As elements in 0ug/L, 1ug/L, 2ug/L, 5ug/L, and 10ug/L, respectively , 20ug/L;

(4) Configure the internal standard solution: Weigh the As standard stock solution with a concentration of 1.0mg/mL, take out 100uL of the standard stock solution and place it in a 100mL volumetric flask, and dilute it with a concentration of 7% nitric acid solution to a concentration of 1.0mg/mL. L of internal standard solution.

(5) Measure the standard working solution obtained according to step (3) and the sample digestion solution obtained according to step (1): the standard working solution obtained in step (3), the sample digestion solution obtained in step (1), and the blank The digestion solution is introduced into the inductively coupled plasma atomic emission spectrometer, that is, the ICP-AES instrument, mixed before entering the nebulizer, and the best isotope of the As element is selected for measurement; the first measurement is performed by adding an internal standard solution online, and the standard working solution is measured first. Then according to the known content of As element in the standard working solution and the As element response value measured by the inductively coupled plasma atomic emission spectrometer, that is, the ICP-AES instrument, the standard working curve of As element is drawn respectively, and then the sample digestion solution and the blank digestion solution are determined. The response value of each element in the solution is calculated according to the standard working curve to obtain the concentration value of each element in the blank digestion solution and the concentration value of the As element in the sample digestion solution, so as to calculate the concentration value according to the conventional methods in this field

The working parameters of the inductively coupled plasma spectrometer in the step (2) are: radio frequency power 1000W, plasma gas flow rate 20.0L/min, and integration time 20s. Nebulizer flow rate 0.3L/min, auxiliary gas flow rate 1.80L/min,

For the inductively coupled plasma atomic emission spectrometer in the step (5), the operating parameters are: radio frequency power 1000W, carrier gas flow rate 0.75L/min, compensation gas flow rate 0.2L/min, atomization temperature 2°C, and integration time of 0.5s, repeated 3 times.

The arsenic solution can be well prepared by the above-mentioned high-pressure digestion method for convenient testing. The ICP-AES method can solve matrix interference very well with high accuracy.

Detailed ways

The present invention will be described in further detail below in conjunction with the examples, but the examples of the present invention are not limited thereto.

1. Instruments and equipment used in the experiment

100mL high-pressure digestion tank: composed of polytetrafluoroethylene liner and stainless steel tank jacket

2. The working parameters of the instruments and equipment used in the experiment

2.1 Working parameters of inductively coupled plasma atomic emission spectrometer, that is, ICP-AES instrument:

RF power: 1000W

Atomizer flow rate: 0.3L/min

Auxiliary air flow: 1.80L/min

Integration time: 20s

3. Reagents used in the experiment

Ultrapure water (homemade)

30% hydrogen peroxide (excellent grade)

70%, 7% nitric acid (electronic grade)

Configuration of blank digestion solution: directly add 8-14mL of 90% nitric acid and 1-5mL of 30% hydrogen peroxide into a 100mL high-pressure digestion tank to make a sample solution, tighten the tank cover, and then place the high-pressure digestion tank containing the sample solution ;Turn on the program control system, set the blast drying oven to heat up to 200°C-205°C, turn off the power after 5-10 hours of constant temperature, and then cool down naturally; after the end, open the tank cover, put the sample liquid in the fume hood to stand still, When the sample solution is clear, transfer it to a 25mL plastic volumetric flask, and dilute it to 25mL with ultrapure water to obtain a blank digestion solution; the configuration of the standard working solution: Weigh the As element standard stock solution with a concentration of 1.0mg/mL, from which Take out 100uL of the standard stock solution and place it in a 100mL volumetric flask, dilute it with 90% nitric acid solution to a standard solution mother solution with a concentration of 1.0mg/L, and then take out the standard solution of 0uL, 10uL, 20uL, 50uL, 100uL, and 200uL respectively. The mother liquor of the solution was placed in a 10mL volumetric flask respectively, and was diluted with a 7% nitric acid solution to form a standard working solution. L, 1ug/L, 2ug/L, 5ug/L, 10ug/L, 20ug/L;

4. Test steps

4.1 Embodiment 1

Weigh 0.50g of environmental samples and place them in a 100mL high-pressure digestion tank, add 60% potassium permanganate solution and let it stand for 10 minutes, then add 10-20mL of 90% nitric acid and 2-5mL of 20% hydrogen peroxide to make a sample solution , and then put the high-pressure digestion tank containing the sample liquid into the blast drying oven; turn on the program control system, set the blast drying oven to heat up to 200 ° C ~ 205 ° C, turn off the power after a constant temperature of 5 ~ 10 hours, and cool naturally; Place the sample solution for ventilation until the sample solution is clear, then transfer it to a 50mL plastic volumetric flask, and dilute to 25mL with ultrapure water to obtain a sample digestion solution. The digestion solution obtained above was measured with an inductively coupled plasma atomic emission spectrometer, ie, an ICP-AES instrument, to measure the spectral intensity of the arsenic element contained in the digestion solution at 193.696 nm.

The content of arsenic element in the digestion solution is quickly determined by ICP-AES method: first, weigh the As element standard stock solution with a concentration of 1.0mg/mL, take out 100uL standard stock solution from it and place it in a 100mL volumetric flask, and use 7% nitric acid The solution is diluted into a standard solution mother solution with a concentration of 1.0 mg/L, and then the standard solution mother solutions of 0uL, 10uL, 20uL, 50uL, 100uL, and 200uL are respectively taken out and placed in a 10mL volumetric flask, and diluted with a concentration of 7 nitric acid solution to obtain Standard working solution, the content of As element in the obtained standard working solution of 0uL, 10uL, 20uL, 50uL, 100uL, 200uL is 0ug/L, 1ug/L, 2ug/L, 5ug/L, 10ug/L, 20ug respectively /L;

Weigh the arsenic element standard stock solution with a concentration of 1.0mg/mL, take out 100uL of the standard stock solution and place it in a 100mL volumetric flask, and dilute it with 7% nitric acid solution to form an internal standard solution with a concentration of 1.0mg/L.

Use an inductively coupled plasma atomic emission spectrometer, that is, ICP-AES instrument, to measure the standard working solution and the sample digestion solution: sequentially introduce the internal standard solution - and the standard working solution, the sample digestion solution and the blank digestion solution into the inductively coupled plasma atoms The emission spectrometer, that is, the ICP-AES instrument, is mixed before entering the nebulizer, and the best isotope of the element is selected for determination;

First measure the standard working solution, and then draw the standard working curve of the As element according to the known content of the As element in the standard working solution and the As element response value measured by the inductively coupled plasma atomic emission spectrometer, that is, the ICP-AES instrument, and then determine The response value of each element in the sample digestion solution and the blank digestion solution is calculated according to the standard working curve to obtain the concentration value of each element in the sample digestion solution and the concentration value of the As element in the blank digestion solution, and the content of As is obtained according to a calculation method known in the art .

The invention adopts the high-pressure digestion method to pre-treat the environmental samples, and measures 193.696nm by the ICP-AES method, which solves the loss and pollution of the instrument caused by the incomplete digestion of the high-pressure digestion method or the result deviation caused by the large matrix interference Bigger problem. The As element was quantitatively determined by ICP-AES. The detection limit of the method was between 0.06 and 1.5 μg/kg, and the matrix interference was small, which could meet the needs of production and life.

Claims (3)

1. A method for high-pressure digestion ICP-MS method to measure arsenic content in environmental samples, the steps of described ICP-AES method for measuring As element content in the sample digestion solution are as follows: (1) Weigh 0.2 g ~ 0.6 g of environmental samples and place them in a high-pressure digestion tank with a capacity of 100 mL, add 60% potassium permanganate solution and let it stand for 10 minutes, then add 10-20 mL of 90% nitric acid and 20% peroxide Hydrogen 2 ~ 5mL to make the sample liquid, then put the high pressure digestion tank containing the sample liquid into the blast drying oven; open the program control system, set the blast drying oven to heat up to 200 ℃ ~ 205 ℃, constant temperature time 5 ~ After 10 hours, turn off the power and let it cool naturally; place the sample liquid for ventilation until the sample liquid is clear, then transfer it to a 50mL plastic volumetric flask, and dilute it to 25mL with ultrapure water to obtain a sample digestion solution; in another 100mL high-pressure digestion tank Directly add 60% potassium permanganate solution and let it stand for 10 minutes, then add 10-20mL of 90% nitric acid and 2-5mL of 20% hydrogen peroxide to make sample liquid, and then put the sample liquid into the high-pressure digestion tank In the blast drying oven; open the program control system, set the temperature of the blast drying oven to 200 ° C ~ 205 ° C, turn off the power after a constant temperature of 5 ~ 10 hours, and cool naturally; place the sample liquid for ventilation until the sample liquid is clear, and then Transfer to a 50mL plastic volumetric flask, and dilute to 25mL with ultrapure water to obtain a blank digestion solution; (2) According to the sample digestion solution obtained in step (1), use an inductively coupled plasma spectrometer, that is, an ICP-AES instrument to measure the spectral intensity of the As element contained in the sample digestion solution at 193.696nm, and record the As intensity value; (3) Configure the standard working solution: Weigh the As standard stock solution with a concentration of 2.0mg/mL respectively, take out 100uL of the standard stock solution and place it in a 100mL volumetric flask, add 60% potassium permanganate solution, and use a concentration of 7% The nitric acid solution was diluted into a standard solution mother solution with a concentration of 1.0mg/L, and then the standard solution mother solutions of 0uL, 10uL, 20uL, 50uL, 100uL and 200uL were taken out respectively and placed in a 10mL volumetric flask, respectively Diluted into a standard working solution, the obtained standard working solutions of 0uL, 10uL, 20uL, 50uL, 100uL, and 200uL correspond to the contents of As elements in 0ug/L, 1ug/L, 2ug/L, 5ug/L, and 10ug/L, respectively , 20ug/L; (4) Configure the internal standard solution: Weigh the As standard stock solution with a concentration of 1.0mg/mL, take out 100uL of the standard stock solution and place it in a 100mL volumetric flask, and dilute it with a concentration of 7% nitric acid solution to a concentration of 1.0mg/mL. L of internal standard solution. the (5) Measure the standard working solution obtained according to step (3) and the sample digestion solution obtained according to step (1): the standard working solution obtained in step (3), the sample digestion solution obtained in step (1), and the blank The digestion solution is introduced into the inductively coupled plasma atomic emission spectrometer, that is, the ICP-AES instrument, mixed before entering the nebulizer, and the best isotope of the As element is selected for measurement; the first measurement is performed by adding an internal standard solution online, and the standard working solution is measured first. Then according to the known content of As element in the standard working solution and the response value of As element measured by the inductively coupled plasma atomic emission spectrometer (ICP-AES instrument), draw the standard working curve of As element respectively, and then measure the sample digestion solution and blank digestion The response value of each element in the solution is calculated according to the standard working curve to obtain the concentration value of each element in the blank digestion solution and the concentration value of the As element in the sample digestion solution, so as to calculate the concentration value according to the conventional methods in this field. 2. The method according to claim 1, the inductively coupled plasma spectrometer in the described step (2), the operating parameters are: radio frequency power 1000W, plasma gas flow rate 20.0L/min, integration time 20s. The atomizer flow rate is 0.3L/min, and the auxiliary gas flow rate is 1.80L/min. the 3. The method as claimed in claim 2, the inductively coupled plasma atomic emission spectrometer in the described step (5), the operating parameters are: radio frequency power 1000W, carrier gas flow 0.75L/min, compensation gas flow 0.2L/min min, the atomization temperature is 2°C, the integration time is 0.5s, and the number of repetitions is 3 times. the