Method for improving detection sensitivity of 129I in water measured by triple quadrupole mass spectrometry

Abstract

The invention relates to the technical field of radionuclide measurement, and discloses a method for improving the detection sensitivity of 129I in water measured by triple quadrupole mass spectrometry, which comprises the following steps: step 1, pre-processing a sample; 2, preparing a triple quadrupole mass spectrum; 3, measuring a sample; according to the method, the required volume of the sample amount in a conventional method is changed, a to-be-measured sample can be concentrated to 0.1 ml for measurement by changing mass spectrum parameters and a measurement method, and the concentration of the sample is effectively improved by utilizing a concentration method, so that the sensitivity of sample measurement is improved, the sampling amount and the amount of an analysis sample are also changed, and the analysis cost is reduced; according to the method, a conventional stability measurement method is changed, an ultra-trace element to be measured is solved by using an isotope ratio through an instantaneous signal increase phenomenon by utilizing non-stability measurement, and the sensitivity of I in mass spectrum measurement is effectively improved by 30 times to the maximum extent.

Description

Technical Field

[0001] The present invention relates to the technical field of radionuclide measurement, and in particular to a method for improving the measurement of water by triple quadrupole mass spectrometry. 129 I. Method for detecting sensitivity. Background Art

[0002] 129 I is the only long-lived radioactive isotope of iodine, with a half-life of 1.6×10 7 It is mainly produced by the fission reaction of uranium and plutonium. With the development of nuclear technology, nuclear tests, spent fuel reprocessing and nuclear power plant accidents have released or leaked a large amount of 129 I, make the environment 129 I and 127 I abundance ratio increased rapidly by 2-4 orders of magnitude. 129 I has a very long lifespan, is extremely active in chemical properties, and is easily mobile in groundwater. 129 The migration of I into surface water or groundwater is of great significance for the study of hydrological tracing, radioactive migration laws and other environmental processes.

[0003] The triple quadrupole mass spectrometer has high sensitivity, low detection limit, multi-element detection, wide linear dynamic range and isotope analysis capabilities, and is the most powerful analytical equipment for trace element determination. In recent years, many workers have used triple quadrupole to measure the 129 I. However, because of the environment 129 The content of I is very low, and the sensitivity of the triple quadrupole is no longer in line with the actual detection standard required. 129 I, often requires several liters or even dozens of liters of water samples for enrichment and purification, which makes collection and transportation difficult, the process is long and the efficiency is low.

[0004] To this end, we proposed a limiting volume redox method to measure 129 I is designed to solve the above problems and achieve higher analyte detection sensitivity with minimal sample volume. Summary of the invention

[0005] The present invention aims at the difficulty of detecting ultra-trace amounts of water in environmental water samples by triple quadrupole mass spectrometry. 129 I, a limiting volume redox triple quadrupole mass spectrometry method is proposed 129 I method, to detect ultra-trace amounts through a small amount of water sample 129 I.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] 1. A method to improve the triple quadrupole mass spectrometry in water 129I. A method for detecting sensitivity, wherein the steps are as follows:

[0008] Step 1: Sample pre-processing;

[0009] Step 2: Triple quadrupole mass spectrometry preparation;

[0010] Step 3: Sample measurement;

[0011] Step 4: Data processing.

[0012] As a further solution of the present invention: the specific steps of the sample pre-treatment in step 1 are as follows:

[0013] S1: Prepare the reagents used;

[0014] 1mol / LH 2 SO 4 , the dosage should not exceed 10ml; 1mol / L NaHSO 3 , dosage is about 1ml; 0.05M NaHSO 3 , dosage is about 1ml; 1mol / L NaNO 2 , use about 2 ml, prepare about 200-500 ml of water sample, filter, remove large impurities, add a certain amount of H 2 SO 4 and NaHSO 3 , the purpose is to reduce the IO 3 - Convert to I - ; Evaporate to reduce the volume to 20-50ml;

[0015] S2: sample desalting and purification;

[0016] Take a double-open round-bottom flask, let air in one end and connect the absorption liquid to the other end, heat and evaporate it with a matching electric heating mantle, collect the prepared absorption liquid, evaporate it to 0.1-0.5ml, and wait for measurement.

[0017] As a further solution of the present invention: in the step 2, the operating parameters are set on the inductively coupled plasma mass spectrometer, argon is used as the carrier gas, and O 2 Mass counts for mode measurement I, O 2 The flow rate is 0.55ml / min, configured 127 I standard solution, and determine the working curve, and use the standard addition method to measure the 127 The concentration of I, the operating parameters of the inductively coupled plasma mass spectrometer were set as follows: power of 1400 W, cooling gas of 14 L / min, auxiliary gas flow of 0.9 L / min, and nebulizer flow rate of 0.9 L / min.

[0018] As a further solution of the present invention: the specific steps of sample measurement in step 3 are as follows:

[0019] S1: Establish a method on mass spectrometry to measure the elements 127 I and 129 I, residence time is 0.05s, sample extraction time is 0, and repeated measurement is 100 times;

[0020] S2: The concentrated sample to be tested is adjusted to a 2%-5% HCl system with a concentration of 5×10 -4 -9×10 -4 NaNO 2 Solution;

[0021] S3: Place the injection tube in the air for about 1 minute, put in the sample, extract about 0.1ml-0.2ml of the sample, click on the measurement, and quickly put the injection tube into the NaNO 2 Solution, rinse with ammonia after measurement.

[0022] As a further solution of the present invention: In step 4, formula (1) is used to calculate the sample 129 I content:

[0023]

[0024] In formula (1):

[0025] 129 I is the sample to be tested 129 I concentration (g / ml);

[0026] 127 I 1 The external standard method is used to determine the 127 C 1 Count rate 127 I concentration (g / ml);

[0027] 127 C 1 For TQ ICP-MS test solution 127 I count rate (cps);

[0028] 129 C 1 , 127 C 2 The peak value of the instantaneous rise in the TQ ICP-MS test liquid 127 I and 129 I count rate (cps);

[0029] k 129 / 127 for 127 I peak tailing and 127 IH2 right 129 I produces interference coefficient;

[0030] 129 C 0 Cause 129 Xe background introduction 129 I count rate (cps).

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention changes the required volume of the sample in the conventional method. By changing the mass spectrometry parameters and the measurement method, the sample to be tested can be concentrated to 0.1 ml for measurement. The concentration method is used to effectively increase the sample concentration, thereby improving the sensitivity of sample measurement, and also changing the sampling amount and the amount of analyzed samples, thereby reducing the analysis cost.

[0033] The present invention introduces redox reaction into the sample injection system, uses the spray chamber as a space container for interaction and separation of products, and utilizes I 2 The slightly soluble and volatile properties in water allow the separated substances and the aerosol generated by the nebulizer to enter the plasma together, further improving the analytical performance of ICP-MS;

[0034] The present invention changes the conventional stability measurement method, utilizes the non-stability measurement, and uses the isotope ratio to obtain the ultra-trace element to be measured through the instantaneous increase of the signal, thereby effectively improving the sensitivity of I in mass spectrometry measurement by a maximum of 30 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The triple quadrupole redox method limit volume measurement in Example 1 129 I Schematic diagram.

[0036] Figure 2 Schematic diagram for comparing the sensitivity of the redox method and the conventional measurement method.

[0037] Figure 3 Schematic diagram for comparison of limiting injection volume redox method measurements using 0.1ml-0.5ml samples. DETAILED DESCRIPTION

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

[0039] See also Figures 1 to 3In an embodiment of the present invention, a method for improving the triple quadrupole mass spectrometry in water 129 I. A method for detecting sensitivity, wherein the steps are as follows:

[0040] Step 1: Sample pre-processing;

[0041] The specific steps for sample pre-processing are as follows:

[0042] S1: Prepare the reagents used;

[0043] 1mol / LH 2 SO 4 , the dosage should not exceed 10ml; 1mol / L NaHSO 3 , dosage is about 1ml; 0.05M NaHSO 3 , dosage is about 1ml; 1mol / L NaNO 2 , use about 2 ml, prepare about 200-500 ml of water sample, filter, remove large impurities, add a certain amount of H 2 SO 4 and NaHSO 3 , the purpose is to reduce the IO 3 - Convert to I - ; Evaporate to reduce the volume to 20-50ml;

[0044] S2: sample desalting and purification;

[0045] Take a double-open round-bottom flask, let air in one end and connect the absorption liquid to the other end, heat and evaporate to dryness with a matching electric heating mantle, collect the prepared absorption liquid, evaporate to 0.1-0.5ml, and wait for measurement;

[0046] Step 2: Triple quadrupole mass spectrometry preparation;

[0047] The operating parameters of the inductively coupled plasma mass spectrometer were set to use argon as the carrier gas and O 2 Mass counts for mode measurement I, O 2 The flow rate is 0.55ml / min, configured 127 I standard solution, and determine the working curve, and use the standard addition method to measure the 127 The working parameters of the inductively coupled plasma mass spectrometer were as follows: power of 1400 W, cooling gas of 14 L / min, auxiliary gas flow of 0.9 L / min, and nebulizer flow rate of 0.9 L / min;

[0048] Step 3: Sample measurement;

[0049] The specific steps for sample measurement are as follows:

[0050] S1: Establish a method on mass spectrometry to measure the elements 127 I and 129 I, residence time is 0.05s, sample extraction time is 0, and repeated measurement is 100 times;

[0051] S2: The concentrated sample to be tested is adjusted to a 2%-5% HCl system with a concentration of 5×10 -4 -9×10 -4 NaNO 2 Solution;

[0052] S3: Place the injection tube in the air for about 1 minute, put in the sample, extract about 0.1ml-0.2ml of the sample, click on the measurement, and quickly put the injection tube into the NaNO 2 In the solution, rinse with ammonia after measurement;

[0053] Step 4: Data processing;

[0054] Formula (1) is used to calculate the sample 129 I content:

[0055]

[0056] In formula (1):

[0057] 129 I is the sample to be tested 129 I concentration (g / ml);

[0058] 127 I 1 The external standard method is used to determine the 127 C 1 Count rate 127 I concentration (g / ml);

[0059] 127 C 1 For TQ ICP-MS test solution 127 I count rate (cps);

[0060] 129 C 1 , 127 C 2 The peak value of the instantaneous rise in the TQ ICP-MS test liquid 127 I and 129 I count rate (cps);

[0061] k 129 / 127 for 127 I peak tailing and 127 IH 2 right 129 I produces interference coefficient;

[0062] 129 C 0 Cause 129 Xe background introduction 129 I count rate (cps).

[0063] Embodiment 1

[0064] A method for improving triple quadrupole mass spectrometry in water 129 I. Method for detecting sensitivity, the specific steps of which are as follows:

[0065] Step 1: Filter the water sample to remove larger impurities, take 274g of sample, add 0.5ml 1mol / L NaHSO 3 , use 1mol / LH 2 SO 4 Adjust pH to about 2, heat at 90°C and evaporate to about 40 ml;

[0066] Step 2: Place the evaporated sample in a double-necked round-bottom flask and add 1 mol / L NaNO 2 About 2ml. Air is continuously introduced into one end of the round-bottom flask at a flow rate that allows bubbles to appear in the absorption liquid at the tail end. Two U-shaped tubes are connected in series at the tail end, each containing about 5ml of 5×10 -5 NaHSO 3 Pure water solution, heated in a round bottom flask at 90°C and evaporated to dryness;

[0067] Step 3: Transfer the absorption liquid to a beaker and evaporate it at 50°C. The final volume after evaporation is 0.45 ml.

[0068] Step 4: Adjust the mass spectrometry parameters to the optimal state and set O 2 Mode, O 2 When the flow rate is 0.55ml / min, 129 The interference value of I is less than 10cps. Configuration 127 I standard solution, and determine the working curve, and use the standard addition method to measure the 127 The concentration of I;

[0069] Step 5: Create a method to measure the element 127 I and 129 I, residence time is 0.05s, sample extraction time is 0, and repeated measurement is 100 times;

[0070] Step 6: Adjust the concentrated sample to about 2% HCl system and prepare 5 ml of 9×10 -4 NaNO 2 Solution;

[0071] Step 7: Place the injection tube in the air for about 1 minute, add the sample, extract about 0.2 ml of the sample, click on the measurement, and quickly put the injection tube into the NaNO 2 In the solution, rinse with ammonia after measurement;

[0072] Step 8: Data processing, according to formula (1) to calculate the 129 The concentration of I.

[0073] The sample measurement data in Example 1 is shown in Table 1:

[0074] Table 1 Sample measurement data table

[0075]

[0076] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method to improve the triple quadrupole mass spectrometry in water 129 I. A method for detecting sensitivity, characterized in that: The method steps are as follows: Step 1: Sample pre-processing; Step 2: Triple quadrupole mass spectrometry preparation; Step 3: Sample measurement; Step 4: Data processing.

2. The method for improving the triple quadrupole mass spectrometry in water according to claim 1 129 I. A method for detecting sensitivity, characterized in that: The specific steps of sample pre-processing in step 1 are as follows: S1: Prepare the reagents used; 1mol / L H2SO4, the amount should not exceed 10ml; 1mol / L NaHSO3, the amount should be about 1ml; 0.05M NaHSO3, the amount should be about 1ml; 1mol / L NaNO2, the amount should be about 2ml, prepare about 200-500ml water sample, filter, remove larger impurities, add a certain amount of H2SO4 and NaHSO3, the purpose is to reduce the IO3 in the water - Convert to I - ; Evaporate to reduce the volume to 20-50ml; S2: sample desalting and purification; Take a double-open round-bottom flask, let air in one end and connect the absorption liquid to the other end, heat and evaporate it with a matching electric heating mantle, collect the prepared absorption liquid, evaporate it to 0.1-0.5ml, and wait for measurement.

3. The method for improving the triple quadrupole mass spectrometry in water according to claim 1 129 I. A method for detecting sensitivity, characterized in that: In step 2, the operating parameters are set on the inductively coupled plasma mass spectrometer, argon is used as the carrier gas, the mass spectrum count of I is measured in O2 mode, the flow rate of O2 is 0.55 ml / min, and the configuration 127 I standard solution, and determine the working curve, and use the standard addition method to measure the 127 The concentration of I, the operating parameters of the inductively coupled plasma mass spectrometer were set as follows: power of 1400 W, cooling gas of 14 L / min, auxiliary gas flow of 0.9 L / min, and nebulizer flow rate of 0.9 L / min.

4. The method for improving the triple quadrupole mass spectrometry in water according to claim 1 129 I. A method for detecting sensitivity, characterized in that: The specific steps of sample measurement in step 3 are as follows: S1: Establish a method on mass spectrometry to measure the elements 127 I and 129 I, residence time is 0.05s, sample extraction time is 0, and repeated measurement is 100 times; S2: The concentrated sample to be tested is adjusted to a 2%-5% HCl system with a concentration of 5×10 -4 -9×10 -4 NaNO2 solution; S3: Place the injection tube in the air for about 1 minute, put in the sample, extract about 0.1ml-0.2ml of the sample, click to measure, quickly place the injection tube in the NaNO2 solution, and rinse with ammonia water after the measurement is completed.

5. The method for improving the triple quadrupole mass spectrometry in water according to claim 1 129 I. A method for detecting sensitivity, characterized in that: In step 4, formula (1) is used to calculate the sample 129 I content: In formula (1): 129 I is the sample to be tested 129 I concentration (g / ml); 127 I1 is the external standard method to determine the 127 C1 count rate 127 I concentration (g / ml); 127 C1 is the liquid to be tested in TQ ICP-MS 127 I count rate (cps); 129 C1. 127 C2 is the peak of the instantaneous rise in the TQ ICP-MS test liquid 127 I and 129 I count rate (cps); k 129 / 127 for 127 I peak tailing and 127 IH2 Pair 129 I produces interference coefficient; 129 C0 is the cause 129 Xe background introduction 129 I count rate (cps).

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