阅读说明：本技术 固体样品中痕量重金属汞的x射线荧光快速分析方法 (X-ray fluorescence rapid analysis method for trace heavy metal mercury in solid sample ) 是由 胡学强 倪子月 岳元博 刘明博 于 2021-01-15 设计创作，主要内容包括：本发明涉及一种固体样品中痕量重金属汞的X射线荧光快速测定方法,适合土壤、化肥、食品等样品中的痕量重金属汞的快速检测。方法包括如下步骤：S1、热解析；称取一定质量的固体样品放置到样品热解析单元的气密腔室的样品舟内,升温至600～700℃,实现样品解析；S2、富集；通过载气和载气控制单元控制热解析腔室中的载气流经滤膜,实现滤膜对热解析出来的汞元素的富集；S3、检测；完成富集的滤膜放入样品测试单元进行测试,所述样品测试单元为X射线荧光光谱仪；根据汞的谱峰强度计算滤膜中汞的含量,结合称取的固体样品质量最终计算出样品中汞的含量。本发明不需要对固体样品进行消解等前处理,操作简单,测试快速。(The invention relates to an X-ray fluorescence rapid determination method for trace heavy metal mercury in a solid sample, which is suitable for rapid detection of trace heavy metal mercury in samples such as soil, chemical fertilizers, food and the like. The method comprises the following steps: s1, thermal analysis; weighing a solid sample with a certain mass, placing the solid sample into a sample boat of an airtight chamber of a sample thermal analysis unit, and heating to 600-700 ℃ to realize sample analysis; s2, enriching; the carrier gas in the thermal desorption chamber is controlled to flow through the filter membrane through the carrier gas and carrier gas control unit, so that the mercury element subjected to thermal desorption is enriched by the filter membrane; s3, detecting; putting the enriched filter membrane into a sample testing unit for testing, wherein the sample testing unit is an X-ray fluorescence spectrometer; and calculating the content of mercury in the filter membrane according to the spectrum peak intensity of the mercury, and finally calculating the content of mercury in the sample by combining the mass of the weighed solid sample. The method does not need to carry out pretreatment such as digestion and the like on the solid sample, and has simple operation and quick test.)

1. An X-ray fluorescence rapid analysis method for trace heavy metal mercury in a solid sample uses a heavy metal element analysis system comprising a sample thermal analysis unit, a carrier gas unit, a sample enrichment unit and a sample test unit to carry out testing, and is characterized by comprising the following steps:

s1, thermal analysis:

weighing a solid sample with a certain mass, placing the solid sample into a sample boat of an airtight chamber of a sample thermal analysis unit, and heating to 600-700 ℃ to realize sample analysis;

s2, enrichment:

the carrier gas in the thermal desorption chamber is controlled by the carrier gas unit to flow through the filter membrane, so that the mercury element subjected to thermal desorption is enriched by the filter membrane; the filter membrane can selectively adsorb mercury, and does not contain the element mercury to be detected;

s3, detection:

putting the enriched filter membrane into a sample testing unit for testing, wherein the sample testing unit is an X-ray fluorescence spectrometer; and calculating the content of mercury in the filter membrane according to the spectrum peak intensity of the mercury, and finally calculating the content of mercury in the sample by combining the mass of the weighed solid sample.

2. The method of claim 1, wherein the thermal desorption enrichment of the steps S1 and S2 is performed for 3-5 min.

3. The method of claim 1, wherein in step S1, when the sample boat is placed in the tube of the thermal desorption furnace, the entire thermal desorption furnace forms a hermetic chamber, and the carrier gas enters from the inlet of the tube and passes through the thermal desorption furnace, carrying the mercury thermally desorbed from the sample to be tested to the outlet of the tube.

4. The method as claimed in claim 1, wherein in step S2, the filter membrane is placed at the outlet of the thermal desorption furnace tube to adsorb the element to be detected, thereby enriching the element to be detected in the sample.

5. The method of claim 1, wherein the carrier gas unit powers the carrier gas to flow through the whole system by means of pressurized blowing or negative pressure extraction in step S2.

6. The method of claim 1, wherein the carrier gas is oxygen, argon, or air that is free of elemental mercury.

7. The method of claim 1, wherein the method does not require pretreatment of the solid sample by thermal digestion with a strong oxidizing reagent.

8. The method of claim 1, wherein the solid sample is selected from the group consisting of soil, fertilizer, food, water-based sediment, rock sample.

9. The method of claim 1, wherein the filter membrane is a carbon fiber filter membrane capable of effective adsorption of mercury.

Technical Field

The invention belongs to the field of environmental science, and particularly relates to an X-ray fluorescence rapid analysis method for trace heavy metal mercury in a solid sample.

Background

Mercury has the property of long-range cross-border pollution and is planned as a global pollutant by the environmental planning agency of the united nations. The mercury pollution has the characteristics of durability, easy migration, high biological enrichment, strong toxicity and the like, mercury in the environment can be converted into highly toxic methyl mercury under certain conditions, meanwhile, a human body can absorb mercury and compounds thereof through ways of breathing, digestive tract or skin, and excessive mercury can cause great harm to health.

The standard detection methods of mercury include a cold atomic absorption spectrophotometry for measuring total mercury in soil quality GB/T17136-1997 and an atomic fluorescence method for measuring total mercury, total arsenic and total lead in soil quality GB/T22105-2008, and all the detection methods need to use strong oxidizing acid to digest soil, and have complex pretreatment and complex operation. The standard method of measuring wavelength dispersion X-ray fluorescence spectrometry of inorganic elements of HJ 780 soil and sediment describes the detection of essential elements of arsenic, copper, nickel, lead, zinc and chromium in soil and sediment, but does not describe essential element of mercury; and the minimum standard limit value of agricultural land soil risk control in China is 0.5mg/kg, and the X-ray fluorescence cannot meet the test requirement easily. The prior art discloses a scheme for detecting mercury element by using X-ray fluorescence spectrometry, which is generally directed at a gas sample, for example, the applicant of the present application applied chinese patent ZL 201510257728.7 on 5/19/2015, which provides an 'on-line analyzer and analysis method based on dry enrichment of total mercury in flue gas', and the on-line analysis of total mercury (including gaseous mercury and granular mercury) discharged from flue gas is performed by using an on-line X-ray fluorescence nondestructive detection technology, but the detection limit of the scheme on mercury element is 0.1 μ g/m³And can not be directly used for trace (element content less than one millionth) analysis of solid samples, and the related analysis of trace mercury in solid samples is not seen in the prior artReporting.

Disclosure of Invention

Aiming at the technical problems, the invention aims to provide an X-ray fluorescence rapid analysis method for trace heavy metal mercury in a solid sample.

In order to achieve the purpose, the invention provides the following technical scheme:

an X-ray fluorescence rapid analysis method for trace heavy metal mercury in a solid sample uses a heavy metal element analysis system comprising a sample thermal analysis unit, a carrier gas unit, a sample enrichment unit and a sample test unit to carry out testing, and the method comprises the following steps:

s1, thermal analysis:

weighing a solid sample with a certain mass, placing the solid sample into a sample boat of an airtight chamber of a sample thermal analysis unit, and heating to 600-700 ℃ to realize sample analysis;

s2, enrichment:

the carrier gas in the thermal desorption chamber is controlled by the carrier gas unit to flow through the filter membrane, so that the mercury element subjected to thermal desorption is enriched by the filter membrane; the filter membrane can selectively adsorb mercury, and does not contain the element mercury to be detected;

s3, detection:

putting the enriched filter membrane into a sample testing unit for testing, wherein the sample testing unit is an X-ray fluorescence spectrometer; and calculating the content of mercury in the filter membrane according to the spectrum peak intensity of the mercury, and finally calculating the content of mercury in the sample by combining the mass of the weighed solid sample.

The time for thermal desorption enrichment in the steps S1 and S2 is 3-5 min.

In step S1, when the sample boat is placed in the oven tube of the thermal desorption oven, the entire thermal desorption oven forms an airtight chamber, and the carrier gas enters from the oven tube inlet and flows out to the oven tube outlet while carrying the mercury thermally desorbed from the sample to be tested.

In step S2, the filter membrane is placed at the outlet of the thermal desorption furnace tube to adsorb the element to be detected, thereby enriching the element to be detected in the sample.

In step S2, the carrier gas unit powers the carrier gas by pressurized blowing or negative pressure extraction, and flows the carrier gas through the entire system.

The carrier gas is oxygen, argon or air which does not contain mercury element.

The method does not need to use a strong oxidizing reagent to carry out heating digestion pretreatment on the solid sample.

The solid sample is selected from soil, fertilizer, food, water system sediment and rock sample.

The filter membrane is a carbon fiber filter membrane and can effectively adsorb mercury.

Compared with the prior art, the invention has the beneficial effects that:

the invention realizes the enrichment of mercury in a solid sample through the process of thermal desorption-adsorption, thereby realizing the rapid detection of trace mercury in the sample by the energy dispersion X-ray fluorescence spectrometry. The solid sample is thermally resolved and then adsorbed on the filter membrane to realize enrichment, and then the solid sample is placed into an analyzer for testing, complex pretreatment processes such as soaking and digestion are not needed for the tested solid sample, the whole testing process is simple to operate, and the testing is rapid.

Drawings

FIG. 1 is a spectrum obtained by performing thermal desorption enrichment on a national standard sample GSS4 and then testing the sample by using an X-ray analyzer, wherein a mercury test spectrum peak can be obviously observed;

FIG. 2 is a working curve drawn by using the test intensity as peak intensity and the content as ordinate for the enrichment test of national standard samples with different contents.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

The invention provides an X-ray fluorescence rapid analysis method for trace heavy metal mercury in a solid sample.

The method comprises the following steps:

s1, thermal analysis;

weighing a solid sample with a certain mass, placing the solid sample into a sample boat of an airtight chamber of a sample thermal analysis unit, and heating to 600-700 ℃ to realize sample analysis;

s2, enriching;

the carrier gas in the thermal desorption chamber is controlled by the carrier gas unit to flow through the filter membrane, so that the mercury element subjected to thermal desorption is enriched by the filter membrane; the filter membrane can selectively adsorb mercury, and the filter membrane does not contain the element mercury to be detected.

The time for thermal desorption enrichment is 3 min.

S3, detecting;

putting the enriched filter membrane into a sample testing unit for testing, wherein the sample testing unit is an X-ray fluorescence spectrometer; and calculating the content of mercury in the filter membrane according to the spectrum peak intensity of the mercury, and finally calculating the content of mercury in the sample by combining the mass of the weighed solid sample.

The carrier gas is oxygen, argon or air which does not contain mercury element.

The analysis system used is described below:

the heavy metal element analysis system used in the invention comprises: the device comprises a carrier gas unit, a sample thermal analysis unit, a sample enrichment unit and a sample testing unit. The system can carry out thermal desorption-enrichment on mercury in a solid sample, and finally realizes rapid detection of mercury in the sample by EDXRF. And opening a thermal desorption furnace switch, heating to a set temperature, introducing carrier gas, putting a sample to realize desorption, carrying the desorbed mercury by the carrier gas, enriching by the filter membrane, and directly testing the filter membrane by using an X-ray fluorescence spectrometry to realize the determination of the mercury in the sample.

The carrier gas unit includes: carrier gas, flowmeter, flow control valve, gas circuit. Carrier gas flows through the gas circuit, and carrier gas flow is controlled through the flow control valve, uses the flowmeter to monitor the specific numerical value of carrier gas flow. The carrier gas unit provides power for carrier gas through pressurization blowing or negative pressure extraction, so that the carrier gas flows through the whole system.

The sample thermal desorption unit includes: the device comprises a sample boat, a quartz tube, a silicon-molybdenum rod, a temperature controller, an R-type thermocouple, a gas circuit, a heat insulation material and a fan. The silicon-molybdenum rod heats the quartz tube, the R-type thermocouple can detect the temperature and feed back the temperature to the temperature controller for temperature regulation, the gas circuit restrains the carrier gas and prevents a sample to be detected from diffusing into the air, and the heat insulation material can reduce the heat radiation of the silicon-molybdenum rod to the air. The fan can cool down relevant parts except for the heat preservation material, and the relevant parts of the instrument are guaranteed to work below a certain temperature.

And after the temperature reaches the set temperature, introducing carrier gas into the sample thermal analysis unit. And (3) putting the accurately weighed sample in the sample boat into a thermal analysis furnace chamber, and carrying the analyzed element out by the carrier gas to leave the thermal analysis unit.

Thermal analysis unit during operation places the sample in the sample boat, when opening the temperature controller, if the boiler tube temperature does not reach the temperature that sets up, the temperature controller can control the silicon molybdenum rod and heat the boiler tube, can acquire the temperature of boiler tube through the thermocouple to feedback program control board, when heating the temperature of settlement, the silicon molybdenum rod can stop heating, when the temperature surpassed certain limit, can start cooling device at this moment and cool down, this process can be repeated in the experimentation.

When the sample boat is placed in a furnace tube of the thermal desorption furnace, the whole thermal desorption furnace is a closed space except for a carrier gas inlet and a carrier gas outlet, and the carrier gas enters from the inlet and flows out of the thermal desorption outlet along with mercury thermally desorbed from a sample to be detected when passing through the thermal desorption furnace chamber. The filter membrane placed at the carrier gas outlet can adsorb the element to be detected, so that the element to be detected in the sample is enriched.

The sample enrichment unit comprises a filter membrane and a device for fixing the filter membrane, the carrier gas carries the elements to be detected to flow through the filter membrane, and the filter membrane selectively adsorbs the elements to be detected.

The sample testing unit includes: the X-ray light pipe, the detector, high voltage power supply, control circuit board, industry control touch screen machine. The software of the industrial control touch screen machine controls the filter membrane, the X-ray light pipe, the detector and the high-voltage power supply through the control circuit board to test the element to be tested on the filter membrane, the X-ray light pipe can emit primary X-rays under the control of the high-voltage power supply to irradiate the filter membrane after the mercury is enriched, the element to be tested in the filter membrane is excited to generate characteristic X-rays, the detector receives X-ray photons generated by the sample, the software can analyze a spectrogram received by the detector, and the content of the mercury in the sample to be tested in the sample is calculated and output by combining the weighed sample mass.

Example 1 determination of elemental mercury in soil samples

S1, thermal analysis;

weighing 0.3g of national standard sample GSS4, placing the sample into a sample boat of an airtight chamber of a sample thermal analysis unit, and heating to 650 ℃ to realize sample analysis;

s2, enriching;

controlling argon in the thermal desorption chamber to flow through the filter membrane through the carrier gas and the carrier gas control unit, so as to realize the enrichment of the mercury element subjected to thermal desorption by the filter membrane;

the time for thermal desorption enrichment is 3 min.

S3, detecting;

putting the enriched filter membrane into a sample testing unit for testing, wherein the sample testing unit is an X-ray fluorescence spectrometer; and calculating the content of mercury in the filter membrane according to the spectrum peak intensity of the mercury, and finally calculating the content of mercury in the sample by combining the mass of the weighed solid sample, as shown in figure 1.

FIG. 2 is a working curve drawn by using the method of the present invention to enrich and then test national standard samples with different contents, and using the test intensity as peak intensity and the content as ordinate.