Method for purifying and analyzing chlorine isotope in complex matrix sample

A chlorine isotope and complex matrix technology, applied in the analysis of materials, material analysis by electromagnetic means, material separation, etc., can solve problems such as interference, and achieve the effects of high precision, strong practicability, and high purification efficiency

Inactive Publication Date: 2019-11-01

INST OF HYDROGEOLOGY & ENVIRONMENTAL GEOLOGY CHINESE ACAD OF GEOLOGICAL SCI +1

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Problems solved by technology

In order to better solve the problem of these two types of matrix interference in isotope testing, the present invention discloses a chlorine isotope purification method based on impro...

Abstract

The invention provides a method for purifying and analyzing chlorine isotope in a complex matrix sample. The method comprises the following steps of A, removing organic matters in a sample and purifying the sample; B, removing inorganic interferent from the sample and carrying out separation and purification: B-1, collecting high-purity samples; B-2, selecting an ion chromatographic separation column, and adjusting the inhibition current of a suppressor to be 10-50mA greater than or above of the concentration recommended value of the corresponding eluent, and carrying out gradient elution; B-3, enabling a solution to pass through a microporous filter membrane to be filtered and then performing sampling and sample collection; B-4, carrying out concentration: baking the collected sample on aheating plate to remove a part of moisture; and B-5, enabling the distillate to pass through a cesium cation exchange resin column Cs column to obtain a high-purity cesium chloride solution; and C, carrying out thermal ionization mass spectrometry measurement and correction. The method disclosed by the invention is simple and convenient to operate and high in feasibility; the purification efficiency is extremely high; the purification effect of being close to 100% can be achieved by single purification; and the test background is low, the precision is high, and the method is suitable for batch sample test.

Application Domain

Component separationMaterial analysis by electric/magnetic means

Technology Topic

Collection sampleSample collection +13

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Examples

Experimental program(1)

Example Embodiment

[0035] Example 1:

[0036] To determine the ratio of chlorine isotopes in three types of samples of groundwater, river water and rainwater, the steps are as follows:

[0037] A. Removal of organic matter in samples and sample purification:

[0038] Take a reversed-phase solid-phase extraction cartridge (C18, 1000mg/6.0mlENVI-18, manufactured by SUPELCO), sequentially activate the solid-phase extraction column with 2mL methanol and 10mL pure water, and then pass the sample solution through the activated reversed-phase Solid phase extraction cartridge, the flow rate is controlled at 5mL/min;

[0039] B. Removal, separation and purification of inorganic interferences in samples:

[0040] B-1: Setting of ion chromatography conditions

[0041] Debug the signal trigger device and fraction collector of the isotope-specific preparative ion chromatograph (developed by the Institute of Hydrogeology, Environmental Geology, Chinese Academy of Geological Sciences, Model: Pre-Isotope) to ensure that the instrument can work normally;

[0042] B-2. Choose the IonPacAS23 high-performance chromatographic column produced by Di'an Company in the United States, and prepare a mixed solution of sodium carbonate and sodium bicarbonate as the eluent solution. The concentration of sodium carbonate is 7mM/L and the concentration of sodium bicarbonate is 2mM/L. The principle that the suppressor current is slightly larger than the recommended value and to ensure that the pH of the distillate is neutral or slightly acidic, make sure that the suppressor (ASRS300 produced by Di'an, USA) is set to 70mA;

[0043] B-3: Confirmation of distillate collection time: According to the peak time of chloride ions, combined with the time delay caused by the length of the pipeline, explore and confirm the collection time of distillate; re-inject the collection liquid of different time periods into ions Chromatographic concentration test is performed to calculate the recovery rate, and the time period with the maximum recovery rate is used as the collection time; due to the delay of the pipeline, the main fraction of chloride ions is distilled out within 7-8 minutes, accounting for 65.57% of the total; in the retention time Collect chloride ions for 6-7min, only 11.53% can be collected; a small amount of chloride ions can still be collected at 8-9min and 9-10min; considering that if the time is extended, it may bring other interference ions, so the final choice 6-10min as the best collection time, the collection efficiency is as high as 98.65%.

[0044] B-4: Confirmation of the effect of removing impurities such as nitrate and sulfate

[0045] Select water samples with different contents as simulated samples to confirm the retention time of nitrate ions and sulfate ions. The simulated water sample numbers used in this example are M354, TWS015 and S133 respectively. It is found through experiments that the peak times of nitrate ions are all Between 12min-14min, the peak time of sulfate radicals is between 15-17.5min. According to the chloride ion collection time confirmed in step B-2, collect the sample, and then inject the collected solution into the ion chromatography again. It is found that the interference of nitrate and sulfate distilled between 12-17.7 min has been completely removed.

[0046] B-5 Fraction collection of actual samples of groundwater, river water, rainwater, etc.

[0047] The sample solution obtained in step A is filtered through a microporous membrane with a pore size of 0.22μm, and then loaded. The filtered solution is separated and purified by ion chromatography, and the distillate of the chloride ion peak time period (6.0-10.0min) is collected liquid.

[0048] B-6 Bake the sample on a hot plate to remove part of the water, and then pass the concentrated solution through a cesium cation exchange resin column (Cs column) to obtain a high-purity cesium chloride solution for the next step of isotope analysis;

[0049] C. Determination and calibration of thermal ionization mass spectrometry:

[0050] Coat the high-purity cesium chloride solution obtained in the previous step on the graphite of the thermal ionization mass spectrometer for thermal ionization mass spectrometry. The thermal ionization mass spectrometer is preferably the TritonTI model of Finnigan, and the Faraday cup is used to simultaneously receive ions with masses of 301 and 303. Intensity and calculate the chlorine isotope ratio R cl; Finally, according to the following formula, the R of the above calculation results cl The value is corrected with the known isotope standard value (SMOC) to get the final δ 37 Cl value: among them It is the isotope ratio of the standard substance SMOC.

[0051] The measurement results of this example are shown in the following table:

[0052] Sample serial number Number of measurements δ 37 Cl'[‰]

PUM

Property	Measurement	Unit
Aperture	0.22	µm

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

Simple and efficient operation
Strong implementability

Method for purifying and analyzing chlorine isotope in complex matrix sample

A chlorine isotope and complex matrix technology, applied in the analysis of materials, material analysis by electromagnetic means, material separation, etc., can solve problems such as interference, and achieve the effects of high precision, strong practicability, and high purification efficiency

AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Description & Claims & Application Information

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