阅读说明：本技术 一种测量分析土壤或生物中铅-210的方法 (Method for measuring and analyzing lead-210 in soil or organism ) 是由 方春鸣 姜冬 陆地 于 2021-09-09 设计创作，主要内容包括：本发明提供了一种测量分析土壤或生物中铅-210的方法,所述方法通过铅树脂萃取得到样品液,并经液闪谱仪和电感耦合等离子体-原子发射光谱测量样品液中的铅-210,经本底计数率、探测效率和化学回收率的校正后,计算得出样品中铅-210活度浓度。所述方法实现了对铅-210的快速测量分析,分析周期较传统方法的1-2天缩短为2-3h,操作简单,易批量化,成本低,抗干扰能力强,稳定性和再现性好,铅-210的化学回收率高,适用于多种情况下快速测量环境中铅-210。(The invention provides a method for measuring and analyzing lead-210 in soil or organisms, which comprises the steps of extracting lead resin to obtain sample liquid, measuring lead-210 in the sample liquid through a liquid flash spectrometer and an inductively coupled plasma-atomic emission spectrum, and calculating to obtain the lead-210 activity concentration in the sample after correcting the background counting rate, the detection efficiency and the chemical recovery rate. The method realizes the rapid measurement and analysis of the lead-210, shortens the analysis period to 2-3h compared with the 1-2 days of the traditional method, has the advantages of simple operation, easy batch, low cost, strong anti-interference capability, good stability and reproducibility and high chemical recovery rate of the lead-210, and is suitable for rapidly measuring the lead-210 in the environment under various conditions.)

1. A method of measuring lead-210 in an assay soil or organism, the method comprising:

(1) mixing the pretreatment sample and the lead carrier standard solution to carry out lead enrichment to obtain a lead-containing solution;

(2) purifying and eluting lead in the lead-containing solution by using lead resin, collecting eluent and fixing the volume to obtain a sample solution;

(3) and measuring the sample liquid and the standard solution by adopting an inductively coupled plasma-atomic emission spectrum and a liquid flash spectrometer, and calculating the activity concentration of lead-210 in the sample according to the test result.

2. The method of claim 1, wherein the step of pretreating the sample in step (1) comprises weighing the sample and burning to obtain a pretreated sample;

preferably, the sample is a soil sample or a biological ash sample;

preferably, the burning temperature is 500-700 ℃, preferably 550-650 ℃;

preferably, the burning time is 0.5 to 1.5 hours, preferably 0.8 to 1.2 hours.

3. The method according to claim 1 or 2, wherein the enrichment in step (1) comprises heating the mixed materials under ventilation conditions to keep them boiling, cooling, separating the solid-liquid mixture, evaporating the obtained liquid to obtain mineral crystals, and heating the mineral crystals in an acid solution until the mineral crystals are dissolved to obtain a lead-containing solution;

preferably, the lead carrier standard solution in the step (1) is lead nitrate with the concentration of 10 mg-Pb/mL;

preferably, the mass ratio of the volume of the lead carrier standard solution to the soil sample in the step (1) is 0.99-2.02mL:1g, preferably 0.99-2.002mL:1 g;

preferably, the mixing further comprises concentrated nitric acid and hydrogen peroxide;

preferably, the concentration of the concentrated nitric acid is 7.9-8.1mol/L, preferably 7.99-8.01 mol/L;

preferably, the concentration of the hydrogen peroxide is 29 to 31%, preferably 29.9 to 30.9%;

preferably, the mass ratio of the volume of the concentrated nitric acid to the soil sample is 5-50mL:1g, preferably 10-40mL:1 g;

preferably, the mass ratio of the volume of the concentrated nitric acid to the biological ash sample is 1-25mL:1g, preferably 5-15mL:1 g;

preferably, the mass ratio of the volume of the hydrogen peroxide to the soil sample is 2.5-7mL:1g, preferably 3-6.6mL:1 g;

preferably, the mass ratio of the volume of the hydrogen peroxide to the biological ash sample is 0.5-3.5mL:1g, preferably 1-3mL:1 g;

preferably, the time for keeping boiling is 0.8-1.2h, preferably 0.9-1.1 h;

preferably, the means for separating the solid-liquid mixture comprises filtration or centrifugation;

preferably, the acid solution comprises nitric acid with the concentration of 0.8-1.2mol/L, preferably 0.9-1.1 mol/L;

preferably, the mass ratio of the volume of the acid solution to the soil sample is 13-36mL:1g, preferably 15-30mL:1 g;

preferably, the mass ratio of the volume of the acid solution to the biological ash sample is 2.6-18mL:1g, preferably 3.9-15mL:1 g.

4. A method according to any one of claims 1 to 3, wherein the purification in step (2) comprises transferring the lead-containing solution to a sample tube of a chromatographic column containing a lead resin, draining the solution, subsequently adding nitric acid of a first concentration and nitric acid of a second concentration to the chromatographic column in sequence, with the flow rate being constant, draining the solution, and discarding all effluents of the step;

preferably, the first concentration is 0.9-1.1mol/L nitric acid;

preferably, the second concentration is 0.09-0.11mol/L nitric acid;

preferably, the lead resin is an Eichrom resin produced by triskam, france;

preferably, the liquid flow rate of the discharged liquid in the purification step is 0.5-2.5mL/min, preferably 1-2 mL/min;

preferably, the draining in the purification step is performed under sub-atmospheric conditions;

preferably, the mass ratio of the volume of the lead-containing solution to the lead resin is 15-20mL:1g, preferably 17-18mL:1 g;

preferably, the volume ratio of the nitric acid with the first concentration to the lead-containing solution is 0.6-0.74mL:1 mL;

preferably, the volume ratio of the nitric acid with the second concentration to the lead-containing solution is 1.26-1.4mL:1 mL;

preferably, the volume of the nitric acid with the first concentration is 9-11mL, preferably 9.5-10.5 mL;

preferably, the volume of the nitric acid of the second concentration is 19 to 21mL, preferably 19.5 to 20.5 mL.

5. The method according to any one of claims 1 to 4, wherein the eluting in step (2) comprises eluting the lead-210 by adding citric acid to a chromatographic column, and collecting the eluate;

preferably, the concentration of the citric acid in the elution is 0.0999-0.1001 mol/L;

preferably, the volume of citric acid in the elution is 15-25mL, preferably 18-21 mL;

preferably, the liquid flow rate of the elution is less than 2 mL/min;

preferably, the elution is performed under subatmospheric conditions.

6. The method according to any one of claims 1 to 5, wherein the constant volume comprises heating and evaporating the eluent to a volume of less than 10mL, and transferring the eluent into a colorimetric tube for constant volume to obtain a sample solution.

7. The method of any one of claims 1-6, wherein a liquid flash spectrometer is used in step (3) to measure a background count rate of a background sample liquid and a sample count rate of said sample liquid;

preferably, the liquid flash spectrometer is a Quantum-1220 ultra-low background liquid flash spectrometer;

preferably, the mode of measurement is cpm (normal count mode);

preferably, the input value of the pulse wave analyzer for measuring is 95-105;

preferably, the time of the measurement is 59.5-60.5 min.

8. The method according to any one of claims 1 to 7, wherein in the step (3), the lead-210 signal intensity of the recovery standard solution is measured by using inductively coupled plasma-atomic emission spectrometry, a standard curve of the signal intensity-lead concentration is prepared, the signal intensity of the sample liquid is measured, the lead-210 concentration in the sample liquid is obtained from the standard curve, and the chemical recovery rate of the sample liquid is calculated according to the concentration;

preferably, a detection efficiency standard solution is configured, the counting rate and the signal intensity of the detection efficiency standard solution are measured, and the detection efficiency is calculated.

9. The method according to any one of claims 1-8, wherein the calculating in step (3) comprises: and calculating the lead-210 activity concentration in the sample according to the background counting rate, the sample counting rate, the detection efficiency and the chemical recovery rate.

10. Method according to any of claims 1-9, characterized in that the method comprises the steps of:

(1') pretreatment: weighing a soil sample or a biological ash sample, and burning at the temperature of 500-700 ℃ for 0.5-1.5h to obtain a pretreatment sample;

(2') enrichment: mixing the pretreatment sample with a lead carrier standard solution, concentrated nitric acid and hydrogen peroxide, heating and keeping boiling for 1h, cooling, filtering to obtain a filtrate, evaporating the filtrate to dryness to obtain mineral crystals, and heating the mineral crystals in an acid solution until the mineral crystals are dissolved to obtain a lead-containing solution;

(3') purification: transferring the lead-containing solution into a chromatographic column sample loading tube filled with lead resin, draining, sequentially adding nitric acid with the concentration of 0.9-1.1mol/L and the concentration of 0.09-0.11mol/L into a chromatographic column, keeping the flow rate unchanged, draining, and discarding all effluent liquid in the step;

(4') elution: adding citric acid into the chromatographic column in the step (3') to elute the lead, and collecting the eluent;

(5') constant volume: heating and evaporating the eluent until the volume of the eluent is less than 10mL, and transferring the eluent into a colorimetric tube for constant volume to obtain a sample liquid;

(6') test calculation: and measuring the sample liquid and the standard solution by adopting an inductively coupled plasma-atomic emission spectrum and a liquid flash spectrometer, and calculating the activity concentration of lead-210 in the sample according to the test result.

Technical Field

The invention belongs to the field of radioactivity technical measurement, and particularly relates to a method for measuring and analyzing lead-210 in soil or organisms.

Background

The method is used for quickly and accurately analyzing the radioactive substances, and is the basis and key for food safety monitoring, environmental radiation monitoring and nuclear emergency monitoring. In recent years, the emergency monitoring task of radioactive substances in the fields of import and export trade, agricultural environment, industrial environment, nuclear safety and food safety is increased rapidly, and unprecedented requirements are provided for nuclear and radiation safety work. Radioactive substances have various sources, complex forms, different properties, variable activities, different damage degrees and different emergency disposal methods, and an efficient, accurate and quick radioactive substance analysis method is urgently needed to be developed.

Lead-210 is a long-life beta radionuclide of radioactive uranium system, widely exists in nature, enters human body through inhalation, ingestion or skin and wound contact, and causes internal radiation hazard to human body, wherein ingestion is the main route of lead-210 entering human body. Lead-210 is a very toxic, osteogenic radionuclide, whose daughter bismuth-210 is one of the major contributors to the natural radiation exposure of the human body, while the other daughter polonium-210 is a very toxic alpha radionuclide. Therefore, it is necessary to study the radioactivity level of lead-210 in the environment (including water, soil, biological, mineral, etc. media), and the accurate determination of the activity of lead-210 in the environment media is the basis and precondition for the application study.

A general method (GB/T11713-2015) for high-purity germanium gamma energy spectrum analysis discloses a method for measuring lead-210 in an environment, and a sample is directly placed into an HPGe spectrometer for measurement without complicated chemical pretreatment. The gamma rays emitted by the lead-210 with an energy of 46.5keV will be directly measured by the detector. But its full energy peak energy belongs to the low energy region, and self-absorption coefficient is great, and exploration efficiency is low, and the self-absorption effect strengthens along with the increase of sample thickness, therefore the sample thickness of carrying out the measurement is difficult too big, and the sample size should not be too much promptly. And is also susceptible to interference from other species. Lead-210 activity in environmental samples is inherently low, and a smaller sample size increases the difficulty of gamma ray detection.

Determination of lead-210 in water-crown ether resin chromatography (DB 32/T3584) -2019) discloses a method for determining lead-210 in environmental water and wastewater, and the lower detection limit of the method can reach 2.0 mBq/L. The method is suitable for water samples, wherein a stable lead carrier is added into the water samples, and the stable lead carrier is coprecipitated with ferric hydroxide to adsorb lead elements in carrier water. Dissolving the precipitate with hydrochloric acid, adsorbing lead by crown ether resin, desorbing by ammonium citrate solution, precipitating lead by sodium sulfate, weighing in the form of lead sulfate precipitate, measuring beta ray of bismuth-210 daughter after balancing for one month, and calculating the content of lead-210 in the sample. The standard adopts the latest extraction chromatography and coprecipitation method, is convenient to operate, but needs to be measured after being placed for one month, and cannot be suitable for rapid analysis of emergency and other conditions.

(ISO 13163: 2013)2013 international standard discloses a method for analyzing lead-210 in an environmental water sample. The detection limit is 20 mBq/L. The method mainly comprises the following steps: adding an iron carrier and a lead carrier into a water sample, taking ferric hydroxide as the carrier, adsorbing lead-210 in carrier water, dissolving with acid, adsorbing lead with cation exchange resin, removing lead with weak acid, measuring the recovery rate of lead by using an atomic absorption spectrum or atomic emission spectrometry for a part of eluent, and directly measuring the beta count of the lead-210 by using a liquid scintillation spectrometer for a part of eluent. This standard recommends that measuring the concentration of stable lead using ICP-OES or ICP-MS or AAS, and measuring the beta count of lead-210 using a liquid flash spectrometer, can ensure rapid analysis of lead-210 in a sample, but requires correcting the effect of newly grown bismuth-210 on the measurement (see "Water quality. lead-210-Test method using liquid scanning counting", ISO 13163).

The traditional analysis method for lead-210 in soil has the following defects: (1) the soil has more impurities and more analysis steps; (2) the activity concentration of lead-210 is generally calculated by measuring the activity of daughter bismuth-210, and the analysis period is long.

Disclosure of Invention

Aiming at the problems that the lead-210 analysis period is too long, the detection lower limit is not low enough, so that a small amount of samples cannot be measured and the like in the prior art, the invention provides a method for measuring and analyzing the lead-210 in soil or organisms, the lead-210 in the soil or organisms is measured through lead resin extraction, a liquid flash spectrometer and an inductively coupled plasma-atomic emission spectrum, and the lead-210 activity concentration in the samples is calculated after the background counting rate, the detection efficiency and the chemical recovery rate are corrected, so that the rapid analysis of the lead-210 is realized, and the method has good application prospect.

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

in a first aspect, the present invention provides a method of measuring lead-210 in an assay soil or organism, the method comprising:

(1) mixing the pretreatment sample and the lead carrier standard solution to carry out lead enrichment to obtain a lead-containing solution;

(2) purifying and eluting lead in the lead-containing solution by using lead resin, collecting eluent and fixing the volume to obtain a sample solution;

(3) and measuring the sample liquid and the standard solution by adopting an inductively coupled plasma-atomic emission spectrum and a liquid flash spectrometer, and calculating the activity concentration of lead-210 in the sample according to the test result.

The method uses specific lead resin to adsorb lead in a sample, has high elution efficiency, adopts a liquid flash spectrometer to measure the beta ray counting rate of lead-210 in the desorption solution, directly distinguishes the lead-210 peak by setting a reasonable input value without eliminating the interference of bismuth-210 and polonium-210, adopts Inductively Coupled Plasma-Atomic Emission spectroscopy (ICP-AES) to measure the concentration of a lead carrier in the desorption solution, and has the advantages of shortened time, simple operation, easy batch, low cost, strong anti-interference capability, good stability and reproducibility and higher chemical recovery rate of lead-210 compared with the traditional lead-210 analysis method.

As a preferred technical solution of the present invention, the step of pretreating the sample in step (1) includes weighing the sample and burning the sample to obtain a pretreated sample.

Preferably, the sample is a soil sample or a biological ash sample.

Preferably, the temperature of the burning is 500-700 deg.C, preferably 550-650 deg.C, and may be, for example, 500 deg.C, 550 deg.C, 600 deg.C, 650 deg.C or 700 deg.C, but is not limited to the recited values, and other values not recited in the range of values are also applicable.

Preferably, the burning time is 0.5 to 1.5 hours, preferably 0.8 to 1.2 hours, for example 0.5, 0.8, 1, 1.2 or 1.5 hours, but not limited to the recited values, and other values not recited in the range of values are equally applicable.

As a preferable technical scheme of the invention, the enrichment in the step (1) comprises heating the mixed materials under ventilation condition to keep boiling, cooling, separating a solid-liquid mixture, evaporating the obtained liquid to obtain mineral crystals, and heating the mineral crystals in an acid solution until the mineral crystals are dissolved to obtain the lead-containing solution.

Preferably, the lead carrier standard solution in the step (1) comprises lead nitrate at a concentration of 10 mg-Pb/mL.

Preferably, the mass ratio of the volume of the lead carrier standard solution to the soil sample in step (1) is 0.99-2.02mL:1g, preferably 0.99-2.002mL:1g, and may be, for example, 0.99mL:1g, 1mL:1g, 1.2mL:1g, 1.4mL:1g, 1.6mL:1g, 1.8mL:1g, 2mL:1g, or 2.02mL:1g, but is not limited to the enumerated values, and other non-enumerated values in the range of values are equally applicable.

Preferably, the mixing further comprises concentrated nitric acid and hydrogen peroxide.

Preferably, the concentrated nitric acid has a concentration of 7.9 to 8.1mol/L, preferably 7.99 to 8.01mol/L, and may be, for example, 7.99mol/L, 7.995mol/L, 8.00mol/L, 8.005mol/L, or 8.01mol/L, but is not limited to the recited values, and other values not recited in this range of values are equally applicable.

Preferably, the hydrogen peroxide concentration is 29-31%, preferably 29.9-30.9%, and may be, for example, 29%, 29.2%, 29.4%, 29.6%, 29.8%, 29.9%, 30%, 30.2%, 30.4%, 30.6%, 30.8%, 30.9%, or 31%, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.

Preferably, the mass ratio of the volume of the concentrated nitric acid to the soil sample is 5-50mL:1g, preferably 10-40mL:1g, and may be, for example, 5mL:1g, 10mL:1g, 15mL:1g, 20mL:1g, 25mL:1g, 30mL:1g, 35mL:1g, 40mL:1g, 45mL:1g, or 50mL:1g, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.

Preferably, the mass ratio of the volume of the concentrated nitric acid to the biological ash sample is 1-25mL:1g, preferably 5-15mL:1g, and may be, for example, 1mL:1g, 2mL:1g, 5mL:1g, 10mL:1g, 15mL:1g, 20mL:1g, or 25mL:1g, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.

Preferably, the mass ratio of the volume of hydrogen peroxide to the soil sample is 2.5-7mL:1g, preferably 3-6.6mL:1g, and may be, for example, 2.5mL:1g, 3mL:1g, 3.5mL:1g, 3.9mL:1g, 4mL:1g, 5mL:1g, 6mL:1g, 6.6mL:1g, or 7mL:1g, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.

Preferably, the mass ratio of the volume of the hydrogen peroxide to the biological ash sample is 0.5-3.5mL:1g, preferably 1-3mL:1g, and may be, for example, 0.5mL:1g, 1mL:1g, 1.5mL:1g, 2mL:1g, 2.5mL:1g, 3mL:1g, or 3.5mL:1g, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.

Preferably, the boiling is maintained for a period of time of 0.8 to 1.2 hours, preferably 0.9 to 1.1 hours, for example 0.8, 0.9, 1, 1.1 or 1.2 hours, but not limited to the values listed, and other values not listed in this range are equally applicable.

Preferably, the means for separating the solid-liquid mixture comprises filtration or centrifugation.

Preferably, the filter paper used for the filtration comprises slow speed filter paper.

Preferably, the acid solution comprises nitric acid at a concentration of 0.8-1.2mol/L, preferably 0.9-1.1mol/L, for example 0.8mol/L, 0.9mol/L, 1mol/L, 1.1mol/L or 1.2mol/L, but not limited to the values listed, and other values not listed in this range of values are equally applicable.

Preferably, the mass ratio of the volume of the acid solution to the soil sample is 13-36mL:1g, preferably 15-30mL:1g, and may be, for example, 13mL:1g, 15mL:1g, 18mL:1g, 20mL:1g, 24mL:1g, 25mL:1g, 30mL:1g, or 36mL:1g, but is not limited to the recited values, and other values not recited in this range of values are equally applicable.

Preferably, the mass ratio of the volume of the acid solution to the biological ash sample is 2.6-18mL:1g, preferably 3.9-15mL:1g, and may be, for example, 2.6mL:1g, 3.9mL:1g, 6mL:1g, 12mL:1g, 15mL:1g, or 18mL:1g, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.

As a preferred technical scheme of the invention, the purification in the step (2) comprises transferring the lead-containing solution into a chromatographic column sample loading pipe loaded with lead resin, draining, then sequentially adding nitric acid with a first concentration and nitric acid with a second concentration into the chromatographic column, keeping the flow rate constant, draining, and discarding all effluent in the step.

Preferably, the first concentration of nitric acid is 0.9 to 1.1mol/L, for example 0.9mol/L, 0.95mol/L, 1mol/L, 1.05mol/L or 1.1mol/L, but not limited to the recited values, and other values not recited in the range of values are equally applicable.

Preferably, the second concentration of nitric acid is 0.09mol/L to 0.11mol/L, and may be, for example, 0.09mol/L, 0.095mol/L, 0.1mol/L, 0.105mol/L, or 0.11mol/L, but is not limited to the recited values, and other values not recited in the range of values are also applicable.

Wherein the first concentration nitric acid is used for removing bismuth and iron ions in the lead-containing solution, and the second concentration nitric acid is used for removing plutonium ions in the lead-containing solution.

Preferably, the lead resin is an Eichrom resin produced by triskam, france.

The specific lead resin used in the method is Eichrom resin produced by the French Triskem company, the selectivity of the lead resin is very similar to that of the traditional strontium resin for extracting lead, but the elution is simpler. At 0.01 to 10mol/LHNO₃In the range of (1), the affinity k' value of the lead resin to lead is 20-800, and the lead resin is maximally retained in 1mol/L HNO₃. In the ion concentration range of 0.01-1 mol/L, sodium and calcium do not interfere the adsorption of lead, and when the concentration of potassium is as high as 1mol/L, the adsorption selectivity of lead can still reach 80, so that the adsorption capacity of the lead resin on lead is higher than that of other alkali metal and alkaline earth metal ions and most other cations.

Preferably, the liquid flow rate discharged during the purification step is 0.5-2.5mL/min, preferably 1-2mL/min, and may be, for example, 0.5mL/min, 1mL/min, 1.5mL/min, 2mL/min or 2.5mL/min, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.

Preferably, the draining in the purification step is performed under sub-atmospheric conditions.

Preferably, the mass ratio of the volume of the lead-containing solution to the lead resin is 15 to 20mL:1g, preferably 17 to 18mL:1g, and may be, for example, 15mL:1g, 15.5mL:1g, 16mL:1g, 16.5mL:1g, 17mL:1g, 17.5mL:1g, 18mL:1g, 18.5mL:1g, 19mL:1g, 19.5mL:1g, or 20mL:1g, but is not limited to the values listed, and other values not listed in this range of values are equally applicable.

Preferably, the volume ratio of the nitric acid with the first concentration to the lead-containing solution is 0.6-0.74mL:1mL, and may be, for example, 0.6mL:1mL, 0.64mL:1mL, 0.68mL:1mL, 0.72mL:1mL, or 0.74mL:1mL, but is not limited to the values listed, and other values not listed in this range of values are also applicable.

Preferably, the volume ratio of the nitric acid with the second concentration to the lead-containing solution is 1.26-1.4mL:1mL, and may be, for example, 1.26mL:1mL, 1.3mL:1mL, 1.36mL:1mL, or 1.4mL:1mL, but is not limited to the values listed, and other values not listed in this range of values are also applicable.

Preferably, the volume of nitric acid of the first concentration is 9 to 11mL, preferably 9.5 to 10.5mL, and may be, for example, 9mL, 9.5mL, 10mL, 10.5mL, or 11mL, but is not limited to the recited values, and other values not recited in this range are also applicable.

Preferably, the volume of the nitric acid of the second concentration is 19 to 21mL, preferably 19.5 to 20.5mL, and may be, for example, 19mL, 19.5mL, 20mL, 20.5mL or 21mL, but is not limited to the recited values, and other values not recited in the range of values are also applicable.

As a preferable technical scheme of the invention, the elution in the step (2) comprises adding citric acid into a chromatographic column to elute the lead-210, and collecting the eluent.

Preferably, the concentration of citric acid in the elution is 0.999-1.001mol/L, for example 0.999mol/L, 0.9995mol/L, 1mol/L, 1.0005mol/L or 1.001mol/L, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.

Preferably, the volume of citric acid in the elution is 15-25mL, preferably 18-21mL, and may be, for example, 15mL, 18mL, 20mL, 21mL or 25mL, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.

Preferably, the liquid flow rate of elution is less than 2mL/min, and may be, for example, 0.5mL/min, 1mL/min, 1.5mL/min, or 2mL/min, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.

Preferably, the elution is performed under subatmospheric conditions.

As a preferable technical scheme of the present invention, the constant volume process includes heating and evaporating the eluent until the volume of the eluent is less than 10mL, transferring the eluent into a colorimetric tube, and performing constant volume process to obtain a sample solution.

As a preferred technical solution of the present invention, in the step (3), a liquid flash spectrometer is used to measure the background count rate of the background sample liquid and the sample count rate of the sample liquid.

Preferably, the liquid flash spectrometer is a Quantum-1220 ultra-low background liquid flash spectrometer.

Preferably, the mode of measurement is cpm (normal count mode). This mode is simple to operate and does not require the creation of a lead-210 quenching correction curve.

Preferably, the input value of the pulse wave analyser for measurement is 95-105, for example 95, 96, 97, 98, 99, 100, 101, 102, 103, 104 or 105, but not limited to the values listed, and other values not listed in the range of values are equally applicable.

Preferably, the time of measurement is 59.5-60.5min, such as 59.5min, 59.8min, 60min, 60.2min or 60.5min, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.

In the invention, the Quantum-1220 ultralow background liquid scintillation spectrometer for measuring the counting rate is provided with an alpha/beta pulse waveform analyzer PSA, and alpha/beta rays in a sample can be detected simultaneously by setting a correct PSA value. The optimum PSA value of the instrumental measurement under the experimental conditions was found to be 100 by multiple measurements on a lead-210 standard solution, at which time different peaks of lead-210, bismuth-210 and polonium-210 could be resolved. Therefore, the effect of improving the measurement speed can be achieved through a reasonable input value of the pulse waveform analyzer and the Quantum-1220 ultralow background liquid scintillation spectrometer, and meanwhile, because the method only uses one-time measurement to distinguish the lead-210 peak, the error influence caused by the growth of bismuth-210 and polonium-210 in multiple measurements is avoided, and the accuracy is improved.

The preparation of the background sample solution is to mix 1mol/L nitric acid and lead carrier standard solution in a volume ratio of 20mL:1mL, and to obtain the background sample solution according to the operations of the steps (2 ') - (5').

As a preferable technical solution of the present invention, in the step (3), the signal intensity of lead-210 of the recovery rate standard solution is measured by using inductively coupled plasma-atomic emission spectrometry, a standard curve of the signal intensity-lead concentration is prepared, the signal intensity of the sample liquid is measured, the concentration of lead-210 in the sample liquid is obtained from the standard curve, and the chemical recovery rate of the sample liquid is calculated according to the concentration.

Preparing a recovery rate standard solution by using lead carrier standard solution and constant volume with volume ratios of 0mL to 1000mL, 0.5mL to 1000mL and 1mL to 1000mL respectively, carrying out constant volume to a scribed line by using water, shaking up, measuring the signal intensity of the solution by using ICP-AES, and preparing a signal intensity-lead concentration standard curve.

Preparing a sample solution to be detected according to the volume ratio of the sample solution to the constant volume of 1mL:100mL, fixing the volume to a scribed line by using water, shaking up, measuring the signal intensity of the sample solution by using ICP-AES, and obtaining the concentration of lead in the sample solution through a standard curve.

Preferably, a detection efficiency standard solution is configured, the counting rate and the signal intensity of the detection efficiency standard solution are measured, and the detection efficiency is calculated.

Mixing 1mol/L nitric acid, lead carrier standard solution and lead-210 standard solution according to the volume-mass ratio of 20mL to 1mL to 0.1g (accurate to 0.0001g) to obtain the detection efficiency standard solution, wherein the lead-210 standard solution is prepared by Eckert&Supplied by Ziegler, having a half-life of 22.3. + -. 0.2a, as Pb (NO)₃) Form is dissolved in 1mol/LHNO₃The carrier concentration was 10. mu.g/mL, reference date was 2016.5.1. And (3) according to the operations from the step (2 ') - (5'), measuring the counting rate of the detection efficiency standard solution by using a liquid flash spectrometer, measuring the signal intensity of the detection efficiency standard solution by using ICP-AES, converting according to a standard curve to obtain the lead concentration, calculating to obtain the chemical recovery rate of the lead of the detection efficiency standard solution, and further calculating to obtain the detection efficiency of the instrument.

The method comprises 2 product standard solutions, wherein the first product standard solution is a lead carrier standard solution with the concentration of 10mg-Pb/mL, the medium is distilled water, the other product standard solution is a lead-210 standard solution with the specific activity of 17.7090Bq/g, the medium is 1mol/L nitric acid, lead in the 2 product standard solutions exists in the form of lead nitrate, and only the lead-210 standard solution is an exempt level radioactive source.

The method also comprises 2 standard solutions prepared, wherein one standard solution is a recovery rate standard solution prepared from a lead carrier standard solution and water and is used for drawing a lead-210 concentration standard curve, and the other standard solution is a detection efficiency standard solution prepared from the lead carrier standard solution, the lead-210 standard solution and nitric acid and is used for calculating the detection efficiency of an instrument.

As a preferred embodiment of the present invention, the calculating in step (3) includes: and calculating the lead-210 activity concentration in the sample according to the background counting rate, the sample counting rate, the detection efficiency and the chemical recovery rate.

The chemical recovery rate Y of lead is calculated according to formula (1):

in the formula: chemical recovery of Y-lead,%;

c_s-the concentration of the sample solution, mg-Pb/mL, as converted from the standard curve;

V₁-in step (5'), fixing the volume of the total volume of the eluate, mL;

c₀-the concentration of the lead carrier standard solution in step (2'), mg-Pb/mL;

V₀-volume of lead carrier standard solution in step (2'), mL;

V₃-volume, mL, of sample liquid for ICP-AES measurement;

100-dilution factor correction constant;

the detection efficiency of the low background liquid flash spectrometer on the lead-210 is calculated according to the formula (2):

in the formula: e-efficiency of detection of lead-210,%;

n_a-detecting the count rate, cpm, of the efficiency standard solution;

n_b-background count rate, cpm;

V₁-in step (5'), fixing the volume of the total volume of the eluate, mL;

V₂volume of solution for liquid flash spectrometer measurement, mL;

60-conversion constants in cpm and Bq;

m₀-preparing the mass, g, of the standard solution of detection efficiency added to the standard solution of lead-210; a. the₀-assay activity of lead-210 standard solution, Bq/g;

λ_Pbof lead-210Decay constant, half-life of 22.26 years;

Δt₁-measuring the time interval between the moment and the lead-210 standard solution assay, year;

y-chemical recovery of lead,%, in the detection efficiency test;

the lead-210 activity concentration is calculated according to equation (3):

in the formula: a. the₁-the activity concentration of lead-210 in the sample, Bq/kg;

n_s-sample count rate, cpm;

m-mass of sample, g;

n_b-background count rate, cpm;

e-efficiency,%, calculated for detection of lead-210 by formula (1);

y-chemical recovery of lead calculated by formula (2)%;

V₁-in step (5'), fixing the volume of the total volume of the eluate, mL;

V₂volume of sample liquid for liquid flash spectrometer measurement, mL.

As a preferred embodiment of the present invention, the method comprises the steps of:

(1') pretreatment: weighing a soil sample or a biological ash sample, and burning at the temperature of 500-700 ℃ for 0.5-1.5h to obtain a pretreatment sample;

(2') enrichment: mixing the pretreatment sample with a lead carrier standard solution, concentrated nitric acid and hydrogen peroxide, heating and keeping boiling for 1h, cooling, filtering to obtain a filtrate, evaporating the filtrate to dryness to obtain mineral crystals, and heating the mineral crystals in an acid solution until the mineral crystals are dissolved to obtain a lead-containing solution;

(3') purification: transferring the lead-containing solution into a chromatographic column sample loading tube filled with lead resin, draining, sequentially adding nitric acid with the concentration of 0.9-1.1mol/L and the concentration of 0.09-0.11mol/L into a chromatographic column, keeping the flow rate unchanged, draining, and discarding all effluent liquid in the step;

(4') elution: adding citric acid into the chromatographic column in the step (3') to elute the lead, and collecting the eluent;

(5') constant volume: heating and evaporating the eluent until the volume of the eluent is less than 10mL, and transferring the eluent into a colorimetric tube for constant volume to obtain a sample liquid;

(6') test calculation: and measuring the sample liquid and the standard solution by adopting an inductively coupled plasma-atomic emission spectrum and a liquid flash spectrometer, and calculating the activity concentration of lead-210 in the sample according to the test result.

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

(1) according to the method for measuring and analyzing the lead-210 in the soil or the organism, the lead-210 in the lead resin extraction sample is used, the selectivity to lead elements is high, the elution efficiency is high, multiple extractions in the conventional method are avoided, and the accuracy and the speed of lead-210 detection are improved;

(2) according to the method for measuring and analyzing lead-210 in soil or organism, the liquid flash spectrometer is used for measuring the beta ray counting rate of lead-210 in the analysis liquid, the reasonable input value is set, the interference of bismuth-210 and polonium-210 is not required to be eliminated, the lead-210 peak is directly distinguished, the measuring speed is improved, and the error influence caused by the growth of bismuth-210 and polonium-210 during multiple measurements is avoided;

(3) the method for measuring and analyzing the lead-210 in the soil or the organism, provided by the invention, has the advantages that the analysis period is shortened to 2-3h compared with 1-2 days of the traditional method, the operation is simple, the batch production is easy, the cost is low, the anti-interference capability is strong, the stability and the reproducibility are good, the chemical recovery rate of the lead-210 is high, the method is suitable for various environmental soil and biological ash samples, and the method has great significance in rapidly detecting the lead-210.

Drawings

FIG. 1 is a standard curve graph of signal intensity versus lead concentration for the ICP-AES test in a method provided by an embodiment of the invention.

Fig. 2 is a diagram of a spectrum of a sample liquid in example 1 measured by a liquid flash spectrometer in a cpm mode in the method according to the embodiment of the present invention.

Fig. 3 is a diagram illustrating a spectrum of a sample liquid in example 1 measured by a liquid flash spectrometer in an α/β screening mode according to the method provided by the embodiment of the present invention.

Fig. 4 is a spectrum of a standard lead-210 solution separated by using lead resin measured by a liquid flash spectrometer in an alpha/beta screening mode according to the method provided by the embodiment of the invention.

Detailed Description

For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

In one embodiment, the present invention provides a method for measuring lead-210 in an analytical soil or organism, the method comprising:

(1') pretreatment: weighing 0.5-1g of soil sample or 1-5g of biological ash sample, and burning at the temperature of 500-700 ℃ for 0.5-1.5h to obtain a pretreatment sample;

(2') enrichment: adding 1.00mL of lead carrier standard solution, 20mL of concentrated nitric acid and 3mL of hydrogen peroxide into a pretreated sample, placing the sample on an electric heating plate in a fume hood, heating and keeping boiling for 1h, cooling, filtering to obtain filtrate, evaporating the filtrate to obtain mineral crystals, adding 15mL of nitric acid with the concentration of 1.0mol/L, and heating until the mineral crystals are dissolved to obtain a lead-containing solution;

(3') purification: transferring the lead-containing solution into a chromatographic column sample loading tube filled with lead resin, adjusting the flow rate to be 1-2mL/min, discharging liquid, then sequentially adding 10mL of nitric acid with the concentration of 1.0mol/L and 20mL of nitric acid with the concentration of 0.1mol/L into the chromatographic column, keeping the flow rate unchanged, discharging liquid, and discarding all effluent liquid in the step;

(4') elution: adding 20mL of citric acid with the concentration of 0.1mol/L into the chromatographic column to elute the lead, wherein the flow rate is not more than 2mL/min, and collecting the eluent;

(5') constant volume: heating and evaporating the eluent until the volume of the eluent is less than 10mL, and transferring the eluent into a colorimetric tube for constant volume to obtain a sample liquid;

(6') test calculation: and measuring the sample liquid and the standard solution by adopting an inductively coupled plasma-atomic emission spectrum and a liquid flash spectrometer, and calculating the activity concentration of lead-210 in the sample according to the test result.

Preparing a background sample solution, a recovery rate standard solution and a detection efficiency standard solution, wherein the method comprises the following steps:

background sample solution: adding 1.00mL of lead carrier standard solution into 20mL of nitric acid with the concentration of 1.0mol/L, and preparing a background sample solution according to the operations from the step (2 ') - (5');

recovery standard solution: respectively transferring 0mL, 0.5mL and 1mL of lead carrier standard solution into a 1000mL volumetric flask, diluting with water to a constant volume to be scribed, and shaking up to prepare a recovery rate standard solution;

detection efficiency standard solution: adding 1.00mL of lead carrier standard solution and 0.1g (accurate to 0.0001g) of lead-210 standard solution into 20mL of nitric acid with the concentration of 1.0mol/L, and preparing a detection efficiency standard solution according to the operations from the step (2 ') - (5');

the concentration of the lead carrier is analyzed by using ICP-AES, the characteristic wavelength of lead is 220.353nm, high-purity water is used as a blank, a standard curve of the measured signal intensity-lead concentration is shown in figure 1, the lead content in soil is usually 2-200mg/kg, the lead carrier adding amount in the experiment is 10mg-Pb/mL and is far larger than the lead content in the soil, and the influence on the lead recovery rate can be ignored.

Measuring the background counting rate of the background sample solution by using a liquid flash spectrometer, measuring the signal intensity of a recovery rate standard solution by using an ICP-AES (inductively coupled plasma-atomic emission Spectroscopy) and making a standard curve, measuring the counting rate of the detection efficiency standard solution by using the liquid flash spectrometer, measuring the signal intensity of the detection efficiency standard solution by using the ICP-AES, converting according to the standard curve to obtain the lead concentration, calculating to obtain the chemical recovery rate of the lead in the detection efficiency standard solution, and further calculating to obtain the detection efficiency of the instrument.

Using an instrument:

quantum 1220 type ultralow background liquid scintillation spectrometer (PerkinElmer company)

Optima 8000 type ICP-AES spectrometer (PerkinElmer company)

The working conditions of the instrument are as follows:

operation room temperature: 15-35 ℃; the relative humidity is 30-85%.

The using method of the instrument comprises the following steps:

liquid flash spectrometer: 8.00mL of the solution treated in the step (2 ') - (5') was put into a 20mL scintillation vial, and 12.00mL of Safermix H scintillation fluid prepared in a radiation institute was added, sealed and shaken well. The bottle wall was wiped with alcohol cotton, placed in a low background liquid flash spectrometer, and measured after darkening for 30 min.

ICP-AES: taking 1.00mL of the solution treated in the steps (2 ') - (5') in a 100mL volumetric flask, adding water to fix the volume to the scribed line, shaking up, measuring the signal intensity of the solution by using ICP-AES, and obtaining the concentration of lead in the solution through a standard curve.

And (3) error evaluation:

the accuracy of the measurement results was evaluated by a spiking recovery test, and the recovery calculation formula was as follows:

in the formula: c₁-activity measured after tagging, Bq;

C₂-activity measured before tagging, Bq;

c-labeling Activity, Bq.

It is understood that processes or substitutions and variations of conventional data provided by embodiments of the present invention are within the scope and disclosure of the present invention.

Example 1

The embodiment provides a method for measuring and analyzing lead-210 in soil or organisms, which specifically comprises the following steps:

(1') pretreatment: weighing 1.00g of soil sample, and burning at 500 ℃ for 1.5h to obtain a pretreated sample;

(2') enrichment: adding 1.00mL of lead carrier standard solution, 20mL of concentrated nitric acid and 3mL of hydrogen peroxide into a pretreated sample, placing the sample on an electric heating plate in a fume hood, heating and keeping boiling for 1h, cooling, filtering to obtain filtrate, evaporating the filtrate to obtain mineral crystals, adding 15mL of nitric acid with the concentration of 1.0mol/L, and heating until the mineral crystals are dissolved to obtain a lead-containing solution;

(3') purification: transferring the lead-containing solution to a chromatographic column sample loading tube filled with lead resin of Eichrom-PB-C50-A manufactured by Triskem company, adjusting the flow rate to be 1mL/min, discharging liquid, sequentially adding 10mL of nitric acid with the concentration of 1.0mol/L and 20mL of nitric acid with the concentration of 0.1mol/L into the chromatographic column, keeping the flow rate unchanged, discharging liquid, and discarding all effluent liquid in the step;

(4') elution: adding 20mL of citric acid with the concentration of 0.1mol/L into the chromatographic column to elute the lead, wherein the flow rate is not more than 2mL/min, and collecting the eluent;

(5') constant volume: heating and evaporating the eluent until the volume of the eluent is less than 10mL, and transferring the eluent into a colorimetric tube for constant volume to obtain a sample liquid;

(6') test calculation: and measuring the sample liquid and the standard solution by adopting an inductively coupled plasma-atomic emission spectrum and a liquid flash spectrometer, and calculating the activity concentration of lead-210 in the sample according to the test result.

Example 2

The embodiment provides a method for measuring and analyzing lead-210 in soil or organisms, which specifically comprises the following steps:

(1') pretreatment: weighing 1.00g of biological ash sample, and burning at 700 ℃ for 0.5h to obtain a pretreated sample;

(2') enrichment: adding 1.00mL of lead carrier standard solution, 20mL of concentrated nitric acid and 3mL of hydrogen peroxide into a pretreated sample, placing the sample on an electric heating plate in a fume hood, heating and keeping boiling for 1h, cooling, filtering to obtain filtrate, evaporating the filtrate to obtain mineral crystals, adding 15mL of nitric acid with the concentration of 1.0mol/L, and heating until the mineral crystals are dissolved to obtain a lead-containing solution;

(3') purification: transferring the lead-containing solution to a chromatographic column sample loading tube filled with a lead resin of PB-C50-A manufactured by Eichrom company, adjusting the flow rate to be 2mL/min, discharging the liquid, then adding 10mL of nitric acid with the concentration of 1.0mol/L and 20mL of nitric acid with the concentration of 0.1mol/L into the chromatographic column in sequence, keeping the flow rate unchanged, discharging the liquid, and discarding all effluent in the step;

(4') elution: adding 20mL of citric acid with the concentration of 0.1mol/L into the chromatographic column to elute the lead, wherein the flow rate is not more than 2mL/min, and collecting the eluent;

(5') constant volume: heating and evaporating the eluent until the volume of the eluent is less than 10mL, and transferring the eluent into a colorimetric tube for constant volume to obtain a sample liquid;

(6') test calculation: and measuring the sample liquid and the standard solution by adopting an inductively coupled plasma-atomic emission spectrum and a liquid flash spectrometer, and calculating the activity concentration of lead-210 in the sample according to the test result.

Example 3

The method of measuring and analyzing lead-210 in soil or organisms of example 1 was used to measure and calculate lead-210 in samples, respectively, except that the liquid flash spectrometer used a liquid flash spectrometer without the alpha/beta screening mode.

Comparative example 1

The method of measuring and analyzing lead-210 in soil or organisms according to the above embodiment was used to measure and calculate lead-210 in the sample, respectively, except that strontium resin of model SR-C50-a, manufactured by Eichrom corporation, was used to adsorb the lead.

The sample properties, chemical recovery rates, lead-210 activity concentrations and relative standard deviations of examples 1 to 3 and comparative example 1 are shown in table 1, and the relative standard deviations were calculated by taking a soil sample from the same spot, measuring it by the same operator, the same measuring system, the same operating conditions and the same place, and repeating the measurement 6 times in a short time.

TABLE 1

The relative standard deviations of examples 1 to 3 were 4.8%, 7.2% and 22.6%, respectively, and the relative standard deviation of comparative example 1 was 14.9%, the precision of detection was reduced by example 3 using no α/β discrimination pattern, the relative standard deviation was as high as 22.6%, and the relative standard deviation of comparative example 1 using strontium resin for lead adsorption was 14.9%.

From the examples 1-2, it can be seen that the relative standard deviation of six measurements of the method for measuring and analyzing lead-210 in soil or organisms provided by the invention is less than 7.5%, which proves that the method has high accuracy; the comparison of example 1 and example 3 shows that although the content of lead-210 can be measured by using a liquid flash spectrometer without an alpha/beta screening mode, the detection result obtained by the alpha/beta screening mode is more accurate; the relative standard deviation of the comparative example 1 is higher than that of the example 1, which shows that the invention adopts the specific lead resin with higher selectivity to lead and has high elution efficiency, so that the test result is more accurate and faster, the measurement using the strontium resin is interfered by impurity metal ions, and the accuracy is lower.

FIGS. 2 to 4 are α/β ray spectra obtained when the sample of example 1 was tested using the detailed description, FIG. 2 is an α/β ray spectrum measured using the cpm mode, and two distinct peaks, 150-350ch and 400-700ch, appeared on the spectrum, and it can be preliminarily inferred that the left peak is lead-210 and the right sharp peak is polonium-210, and which peak corresponds to each of lead-210, bismuth-210 and polonium-210 cannot be distinguished; FIG. 3 is an α/β ray spectrum measured by using an α/β discrimination mode, in which three distinct peaks appear on the spectrum, i.e., a short tail pulse or β spectrum, in which two peaks 150-. The lead-210 standard solution is separated by using lead resin and then measured to obtain a graph shown in figure 4, the graph only has a lead-210 peak of 150-350ch, a bismuth-210 peak is not existed, and an alpha spectrum peak of 550-600ch is very low and can be basically ignored. It can be also proved that the lead resin does not adsorb bismuth and has a good effect of separating polonium.

The accuracy is measured by taking a soil sample at the same point, dividing the soil sample into a sample 1, a sample 2 and a sample 3, adding lead-210 standard solutions with different magnitudes respectively, and measuring according to the steps (2 ') - (6') in the example 1, wherein the measurement results are shown in the table 2.

TABLE 2

The standard recovery rate represents the accuracy of the test result, and the closer to 100%, the more accurate the measurement result of the method is proved. The method for detecting lead-210 in soil or organisms provided in example 1 has the advantages that the standard recovery rate is 97-103% after multiple measurements. In conclusion, the method for detecting lead-210 provided by the invention is suitable for rapid analysis of lead-210 in soil or organisms, improves the measurement speed, avoids error influence caused by growth of bismuth-210 and polonium-210 during multiple measurements, shortens the analysis period to 2-3h compared with 1-2 days of the traditional method, is simple to operate, easy to batch, low in cost, strong in anti-interference capability, good in stability and reproducibility, and high in chemical recovery rate of lead-210, is suitable for various environmental soil and biological ash samples, and has great significance in rapid detection of lead-210.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.