阅读说明：本技术 一种快速溶剂萃取-离子色谱法同时检测大气—颗粒物中水溶性阴、阳离子含量方法 (Method for simultaneously detecting water-soluble anion and cation contents in atmosphere-particles by using rapid solvent extraction-ion chromatography ) 是由 余彬彬 严朝朝 涂明阳 张嫣秋 徐方曦 武承林 于 2021-08-24 设计创作，主要内容包括：本发明公开了一种快速溶剂萃取-离子色谱法同时检测大气颗粒物中水溶性阴、阳离子含量方法,涉及大气监测检测领域,其技术方案要点是快速溶剂萃取-离子色谱法的使用,通过标准溶液测试得到阴阳离子标准谱图(附图1和附图2)并得到目标化合物的标准曲线,然后对样品进行预处理并在上机测试结合标准谱图找出相对应的目标峰,再根据标准曲线计算出目标化合物的浓度。整个操作方式,目标化合物的峰型尖锐,响应度强,相对标准偏差小,精密度较好,从而有效地提高了测试的准确度。(The invention discloses a method for simultaneously detecting the content of water-soluble anions and cations in atmospheric particulates by using a rapid solvent extraction-ion chromatography, which relates to the field of atmospheric monitoring detection. In the whole operation mode, the target compound has a sharp peak shape, strong responsiveness, small relative standard deviation and good precision, so that the accuracy of the test is effectively improved.)

1. A method for simultaneously detecting the content of water-soluble anions and cations in atmospheric particulates by using a rapid solvent extraction-ion chromatography is characterized by comprising the following steps of:

(1) collecting a sample of atmospheric particulates;

(2) pretreating a sample to be detected by adopting rapid solvent extraction;

(3) simultaneously analyzing the content of water-soluble anions and cations in the atmospheric particulates by adopting an ion chromatography;

in the step (1), an ambient air particulate matter sampler is used, a dust sampling mode is set, the flow rate is set to be 50-100L/min, and the sampling time is 12-24 h.

And (2) putting the sampled filter membrane into a dryer for balancing for 24 hours, shearing the filter membrane sample along the diameter direction by using a clean ceramic scissors, cutting the filter membrane sample into a fan shape, putting 1/4 pieces to 1 piece into a stainless steel extraction tank, and performing rapid solvent extraction. The quick solvent extraction conditions are that ultrapure water is used as an extracting agent, the extraction temperature is 80 ℃, the pressure is 1500psi, the extraction is carried out twice, each time lasts for 5-10 min, a 33mL extraction cell is adopted, and about 35mL of extraction liquid is obtained each time, and the total volume is about 70 mL. Pouring the extract into a 100mL volumetric flask, preparing 100mL solution by using ultrapure water, shaking uniformly, filtering by a 0.22 mu m microporous filter membrane, and injecting into a sample bottle for ion chromatographic analysis.

In the step (3), the 6 anion analysis conditions are as follows: a chromatographic column: dionex IonPac^TMAS19 anion chromatography column (4X250 mm); column temperature: 35 ℃; leacheate: 20mmol/L KOH solution; the sample volume is 25 mu L; the flow rate is 1 mL/min; the analysis time is 15 min; inhibition of conductance measurements.

6 cation analysis chromatography conditions: chromatographic column Dionex IonPac^TMCS12A cation chromatography column (4X250 mm); column temperature: 35 ℃; leacheate: 20mmol/L LMSA (methanesulfonic acid) solution; the sample volume is 25 mu L; the flow rate is 1 mL/min; the analysis time is 20 min; inhibition of conductance measurements.

2. The method for simultaneously detecting the content of water-soluble anions and cations in atmospheric air-particulates by using the rapid solvent extraction-ion chromatography as claimed in claim 1, wherein the filter membrane in the step 1 is a quartz fiber filter membrane. Soaking the filter membrane with fresh ultrapure water for 20-30min twice before sampling. Then putting the mixture into an oven for drying, and then putting the mixture into a dryer for cooling and balancing for 24 hours.

3. The method for simultaneously detecting the contents of water-soluble anions and cations in atmospheric air-particulates by using the rapid solvent extraction-ion chromatography as claimed in claim 1, wherein the extraction liquid obtained by pretreating the sample and the blank is subjected to sample injection detection under an anion detection system and a cation detection system respectively under the same chromatographic condition as a measurement standard curve, and the sample is subjected to the anion detection and the cation detection by the sample injection simultaneously. And measuring the peak areas of the sample and the blank, calculating the concentrations of the sample and the blank through a standard curve, and subtracting the blank concentration from the calculated sample concentration to obtain the concentration of the actual sample.

Technical Field

The invention relates to a method for simultaneously detecting the content of water-soluble anions and cations in air-particles by using a rapid solvent extraction-ion chromatography, belongs to the field of analysis and detection, and particularly provides a method for detecting 12 water-soluble anions and cations in air dust, which is suitable for detecting water-soluble ions in particles such as PM10 and PM2.5 in the air dust.

Background

The atmospheric dust pollution is a topic of intense interest in recent years in China, and researches show that fine particles in the atmospheric dust pollution can enter human bodies through a respiratory system and cause great harm to the respiratory system and a cardiovascular and cerebrovascular system. With the increase of national monitoring strength and the increase of treatment capacity, the large-range continuous haze weather in China is well controlled. PM2.5 is the concentration limit value of particulate matters (the particle size is less than or equal to 2.5 mu m) in the air quality standard, and mainly comprises water-soluble ions, trace elements, particulate organic matters and the like. PM2.5 is first listed as one of the monitoring indexes of air quality detection in 1997 in the United states. The monitoring of particulate matters such as PM2.5 and the like in China is now normalized.

Sources of atmospheric dust particulates are divided into natural sources and man-made sources, and natural sources include: wind-blown dust, volcanic ash, forest fires, pollen, fungal spores, and the like. Artificial sources include: road dust, building construction dust, kitchen fumes, industrial dust and the like. The mechanism and process of forming PM2.5 in the atmospheric dust particulate matter are complex and can be divided into primary particulate matter and secondary particulate matter. Water soluble ions in the atmospheric dust particles are a key factor in reducing visibility and acid deposition. The water-soluble ionic component is an important component of the atmospheric dust particles and mainly comprises F^-、Cl^-、Br^-、NO₂ ^-、NO₃ ^-、SO₄ ^2-、Li⁺、 K⁺、Na⁺、Mg²⁺、Ca²⁺、NH₄ ⁺And the like. Wherein NO₂ ^-、NO₃ ^-、SO₄ ^2-Is the main component of acid rain. Therefore, the method has important significance in the determination of water-soluble anions and cations in the atmospheric dust.

A common analysis method for water-soluble anions and cations in atmospheric dust is ultrasonic extraction-ion chromatography, and ultrasonic extraction is long in time consumption and easy to introduce process environment impurities. The defect of ultrasonic extraction can be avoided by adopting a rapid solvent method, and an analysis method for simultaneously analyzing water-soluble anions and cations in the atmospheric dust particles by adopting the rapid solvent extraction-ion chromatography is not reported.

Disclosure of Invention

The invention aims to provide a method for simultaneously detecting the content of water-soluble anions and water-soluble cations in atmospheric particulates by using a rapid solvent extraction-ion chromatography, and the method can be used for rapidly and accurately detecting the content of 12 water-soluble anions and water-soluble cations in the atmospheric particulates and has important significance for guaranteeing the ecological environment.

The aim of the invention is realized by the following operation steps:

1) collection of atmospheric particulate samples: in the dust sampling mode, the flow rate is set to be 50-100L/min, and the sampling time is 12-24 h. The sampling filter membrane is a quartz fiber filter membrane, and the filter membrane is soaked in ultrapure water for 20-30min for twice before sampling. Then putting the mixture into an oven for drying, and then putting the dried mixture into a dryer for cooling and balancing for 24 hours for later use;

2) performing sample pretreatment by rapid solvent extraction: after the sampled quartz fiber filter membrane is put into a dryer to be balanced for 24 hours, the filter membrane is cut along the diameter direction by using a clean ceramic scissors to be cut into a fan shape, and 1/4-1 pieces of the filter membrane are put into a 33mL stainless steel extraction pool. Under the set mode, the temperature is 80 ℃, the extraction pressure is 1500psi, and the extraction is carried out twice, 5min each time, and 10min in total. Each extract was about 35mL, for a total of about 70 mL. Pouring the extract into a 100mL volumetric flask, preparing 100mL solution by using ultrapure water, shaking uniformly, filtering by a 0.22 mu m microporous filter membrane, and injecting into a sample bottle for ion chromatographic analysis.

3) The sample was analyzed by ion chromatography.

Drawing a standard curve: preparation of an anionic standard intermediate solution: taking 6 anions (F)^-、Cl^-、NO₂ ^-、Br^-、NO₃ ^-、 SO₄ ^2-) Mixing 1mL (200-1000mg/L) of standard solution, placing the mixture in a 100mL volumetric flask, adding ultrapure water to the scale mark, shaking uniformly, and pouring the mixture into a 1.5mL sample bottle. The standard intermediate solution was pipetted at 10. mu.L, 30. mu.L, 50. mu.L, 100. mu.L, 200. mu.L, 300. mu.L, 400. mu.L and 500. mu.L, respectively, and placed in a sample bottle with ultrapure water added to 1mL, and shaken well for use.

Preparation of cationic standard intermediate solution: taking 6 kinds of positive ions (Li) for ion chromatography⁺、Na⁺、NH₄ ⁺、K⁺、Mg²⁺、Ca^{2 +}) 1mL each of the standard solution (1000mg/L) and the lithium ion standard solution (1000mg/L) for ion chromatography was mixed, placed in a 10mL volumetric flask, added with ultrapure water to the scale, shaken well, and poured into a 1.5mL sample bottle. The standard intermediate solution was pipetted at 5. mu.L, 10. mu.L, 20. mu.L, 30. mu.L, 40. mu.L and 50. mu.L, respectively, and the pipetted solutions were put into a sample bottle and ultrapure water was added to 1mL, and shaken up for use.

Preparing 12 kinds of mixed standard series solutions of anions and cations, performing inhibition conductivity method measurement according to the chromatographic conditions, and drawing a standard curve. F^-：y＝0.4121x-0.0020，Cl^-：y＝0.266x-0.0045，NO₂ ^-：y＝0.1794x-0.0036，Br^-： y＝0.1070x-0.0031，Br^-：y＝0.1070x-0.0031，NO₃ ^-：y＝0.1577x-0.0144，SO₄ ^2-：y＝0.1720x-0.0070， Li⁺：y＝0.7254x-0.0001，Na⁺：y＝0.2324x-0.00003，NH₄ ⁺：y＝-0.015x²+0.2575x+0.0044，K⁺： y＝0.1511x-0.000001，Mg²⁺：y＝0.3690x-0.00003，Ca²⁺：y＝0.2003x-0.00003。

Interference is very easily introduced in the analysis process of water-soluble anions and cations, and the requirement on the blank background of the filter membrane is higher. The invention analyzes the background value of the blank filter membrane, and analyzes the contents of 12 water-soluble anions and cations in the blank filter membrane by soaking the same blank filter membrane in ultrapure water once, twice, three times, four times and five times, and the result is shown in figure 3. Background interference mainly comes from interference of anions, and after the filter membrane is soaked for the second time, the detection value of the anions in the background value of the filter membrane tends to be stable, so that a blank filter membrane treatment mode is performed by adopting ultrapure water to soak for two times.

The conditions of rapid solvent extraction have a large influence on the extraction efficiency. The invention optimizes the temperature and time of the rapid solvent extraction in the test process. The experiments were carried out at 40 ℃ and 80 ℃ respectively. The result shows that the average recovery rate of the ions is better at 80 ℃, the average recovery rate of 12 ions reaches more than 70%, the recovery rate of individual ions is lower at lower temperature, and the extraction is incomplete. The extraction temperature was therefore set to 80 ℃. The experiment compares the ion analysis chromatograms of the extraction solvent of 5min each time of twice circulating extraction and 10min each time of twice circulating extraction. It was found that the extraction solvent obtained by the two-time 10-min extraction was found to contain other impurities, and that the average recovery rate did not increase significantly with respect to the 5-min extraction. In addition, an increase in extraction time resulted in an increase in extractant, so the time was determined to be 5min each time for two extractions in cycles.

Preferably, the 6 anion analysis conditions in step (3) are: a chromatographic column: dionex IonPac^TMAS19 anion chromatography column (4X250 mm); column temperature: 35 ℃; leacheate: 20mmol/L KOH solution; the sample volume is 25 mu L; the flow rate is 1 mL/min; the analysis time is 15 min; inhibition of conductance measurements.

6 cation analysis chromatography conditions: chromatographic column Dionex IonPac^TMCS12A cation chromatography column (4X250 mm); column temperature: 35 ℃; leacheate: 20mA mol/L LMSA (methanesulfonic acid) solution; the sample volume is 25 mu L; the flow rate is 1 mL/min; the analysis time is 20 min; inhibition of conductance measurements.

The selection of the mobile phase and the elution program directly influences the separation effect of the liquid chromatogram, a plurality of mobile phase systems are tested in the test process, a mixed standard cation solution with the concentration of 1.0mg/L is selected, the sample size is 20 mu L, and the separation time is 18 min. The elution conditions of methanesulfonic acid at three different concentrations of 15, 20 and 25mmol/L were compared. The results show that the peak shape is relatively sharper when the concentration of the methanesulfonic acid is high, but the peak emergence time is also early, which is not beneficial to Mg²⁺、Ca²⁺Baseline separation of the two ions. Therefore, after comprehensive comparison, a methanesulfonic acid elution system with the concentration of 20mmol/L is selected, and satisfactory results can be obtained on peak shape, ion separation and peak time.

Preferably, in step (3), 12 anions and cations in the treated sample are quantitatively determined by an external standard method.

In summary, the present invention has the following benefits:

the invention realizes the detection method for simultaneously analyzing 12 water-soluble anions and cations in atmospheric particulates by using the rapid solvent extraction-ion chromatography for the first time. The method has the advantages that the precision, the accuracy and the stability meet the requirements of quantitative analysis, the method has the characteristics of high accuracy, good reproducibility, stability and reliability, and can be used for monitoring the quality of the atmospheric environment and providing technical support for the ecological environment.

Aiming at a target compound, a rapid solvent is adopted to extract water-soluble anions and cations in a sample, the using amount of the solvent is small, the automatic separation of a membrane and an extraction liquid can be realized, the extraction process is relatively closed, the interference of the introduction of foreign impurities on an experiment is reduced, and the method is suitable for the detection of water-soluble ions in particulate matters such as PM10 and PM2.5 in atmospheric dust.

Drawings

FIG. 1 shows a schematic view of a preferred embodiment F^-、Cl^-、Br^-、NO₂ ^-、NO₃ ^-、SO₄ ^2-Ion chromatograms of six anions;

FIG. 2 shows Li in the first embodiment⁺、K⁺、Na⁺、Mg²⁺、Ca²⁺、NH₄ ⁺Ion chromatograms of six cations;

FIG. 3 is a graph showing background effect test of different extraction times on blank filters in the first example;

Detailed Description

The technical solution of the present invention will be further described in detail with reference to specific embodiments. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.

Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

The instrument and drug specifications used in the following examples were:

the instrument comprises the following steps: a rapid solvent extraction apparatus (Dyan corporation, ASE300) equipped with a stainless steel extraction cell, a glass bottle, ICS-5000⁺Ion chromatograph (Thermo corporation), with ICS-5000⁺DP type mobile phase infusion pump (Thermo corporation), ICS-5000⁺EG type drip washing liquid generator (Thermo corporation), ICS-5000⁺AS-AP type autosampler (Thermo Co.), cation electrolytic regeneration suppressor (Thermo Co.), anion electrolytic regeneration suppressor (Thermo Co.), conductance detector (Thermo Co.), Dionex IonPac^TMCS12A cation column (Thermo, specification: 4X250mm), CG12A ion chromatography guard column (Thermo, specification: 2X 50mm) Dionex IonPac^TMAS19 anion chromatographic column (Thermo corporation, specification: 4X250mm), AG19 ion chromatographic guard column (Thermo corporation, specification: 2X 50mm), water phase needle type filter (Shanghai' an spectral science apparatus, Inc., 0.22 μm, phi 13mm), disposable medical injector, ZC-Q0102 intelligent comprehensive atmosphere sampler (Zhejiang Hengda apparatus, Inc.), quartz fiber filter membrane (Ahlstrom corporation), Milli-Q ultrapure water device (MILLIPORE, USA).

Drugs and reagents: ultrapure water, 5 kinds of cation mixed standard solutions (1000mg/L, Beijing Tan ink science Co., Ltd.) for ion chromatography, lithium ion standard solutions (1000mg/L, Beijing Tan ink science Co., Ltd.) for ion chromatography, 7 kinds of anion mixed standard solutions (1000mg/L, Beijing Tan ink science Co., Ltd.), KOH anion leacheate (analytical purity, Thermo Co., Ltd.), and LMSA cation leacheate (analytical purity, Thermo Co., Ltd.).

Anion analysis chromatography conditions: a chromatographic column: dionex IonPac^TMAS19 anion chromatography column (4X250 mm); column temperature: 35 ℃; leacheate: 20mmol/L KOH solution; the sample volume is 25 mu L; the flow rate is 1 mL/min; the analysis time is 15 min; inhibition of conductance measurements.

Cation analysis chromatography conditions: chromatographic column Dionex IonPac^TMCS12A cation chromatography column (4X250 mm); column temperature: 35 ℃; leacheate: 20mmol/L LMSA (methanesulfonic acid) solution; the sample volume is 25 mu L; the flow rate is 1 mL/min; the analysis time is 20 min; inhibition of conductance measurements.

Example a Rapid solvent extraction ion chromatography simultaneous analysis of 12 water-soluble anions and cations

1. Sample collection pretreatment

Soaking the quartz fiber filter membrane in ultrapure water for 20-30min twice before sampling. And then putting the filter membrane into an oven for drying, then putting the filter membrane into a dryer for cooling and balancing for 24 hours, taking the filter membrane, and putting the filter membrane into a particulate matter sampler, wherein the flow rate is set as 100L/min and the sampling time is 12 hours in a dust sampling mode.

After the sampled quartz fiber filter membrane was put into a desiccator and equilibrated for 24 hours, the filter membrane was cut with a clean ceramic scissors in the direction of the diameter, and the filter membrane was cut into a fan shape, and 1/4 pieces were taken and put into a 33mL stainless steel extraction cell. Under the set mode, the temperature is 80 ℃, the extraction pressure is 1500psi, and the extraction is carried out twice, 5min each time, and 10min in total. Pouring the extract into a 100mL volumetric flask, preparing 100mL solution by using ultrapure water, shaking uniformly, filtering by a 0.22 mu m microporous filter membrane, and injecting into a sample bottle for ion chromatographic analysis.

2. Drawing a standard curve

Configuration F^-、Cl^-、Br^-、NO₂ ^-、NO₃ ^-、SO₄ ^2-The series of 6 kinds of anion mixed standard solutions with the sample amount of 20 microlitres are used for drawing a standard curve. Additionally arrange Li⁺、K⁺、Na⁺、Mg²⁺、Ca²⁺、NH₄ ⁺The series of 6 kinds of cation mixed standard solutions with the sample amount of 20 μ L are used for drawing a standard curve, and the sampling volume of air is 60m³The detection limit was calculated (standard state) as 3 times the signal-to-noise ratio (S/N), see Table 1.

Wherein the anion chromatographic column is Dionex IonPac^TMAS19 anion analytical column (4X250mm), and AG19 ion chromatographic protective column (Thermo corporation, specification: 2X 50mm), and the cation chromatographic column is Dionex ion Pac^TMCS12A cation chromatography column (4X250mm), and CG12A ion chromatography guard column (Thermo company, specification: 2X 50 mm).

TABLE 1 method for measuring 12 anion and cation mixed standard solutions by ion chromatography

Example two precision experiments

6 kinds of anion mixed standard solutions with low, medium and high concentrations and 6 kinds of cation standard solutions are respectively dripped on the filter membrane after sampling pretreatment, after sample pretreatment, analysis is carried out under the condition of analytical chromatography, each concentration is parallel 7 times, and the Relative Standard Deviation (RSD) is calculated, which is shown in Table 2.

TABLE 2 Water soluble ion precision test results

Slave watchIt can be seen that: the standard deviation of the anions with low, medium and high concentrations is 0.0019-0.1264 mg/L, the relative standard deviation is 0.7% -19.7%, except low concentration Cl^-In addition, each group has relatively good precision. The standard deviation of the cations is between 0.0081 and 0.0.2397mg/L, the relative standard deviation is between 0.7 and 11.7 percent, and the precision of each group is relatively good.

Example three spiking recovery experiments

The filtration membrane was pretreated before sampling according to step 1, and mixed standard solutions about equivalent to 0.1mg/L, 2mg/L and 4mg/L after extraction were added dropwise, respectively, as additive amounts, to conduct recovery tests, and the results are shown in Table 3.

TABLE 3 Water soluble ion recovery test results

As can be seen from the table: the average recovery rate of the 12 anions and cations is 73.8 to 128.3 percent, except Br^-The external recovery rate is within the range of 70-120%. The precision and the standard adding recovery rate show that the data measured by the method is more accurate and reliable.

Example four methodological validation

After the filter membrane is subjected to sampling pretreatment, sampling is carried out for two hours at a position near an environmental monitoring central station in Taizhou city, the flow rate is 100L/min, and the sampling amount is 12m³And taking 3 parts of sampling membrane, pretreating the sample, and then carrying out sample injection analysis, wherein the mass concentration is shown in table 4.

TABLE 4 analysis results of anions and cations (μ g/m) of the samples³)

Note: n.d. -no detection.