CN114813904A - Method for analyzing isotope composition of ultra-trace element sample - Google Patents
Method for analyzing isotope composition of ultra-trace element sample Download PDFInfo
- Publication number
- CN114813904A CN114813904A CN202210447863.8A CN202210447863A CN114813904A CN 114813904 A CN114813904 A CN 114813904A CN 202210447863 A CN202210447863 A CN 202210447863A CN 114813904 A CN114813904 A CN 114813904A
- Authority
- CN
- China
- Prior art keywords
- sample
- diluent
- isotope
- standard solution
- standard
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
- G01N27/626—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using heat to ionise a gas
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Sampling And Sample Adjustment (AREA)
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
Abstract
The invention discloses a method for analyzing the isotopic composition of an ultra-trace element sample. Firstly, preparing a standard solution with a high diluent/sample ratio, and obtaining the isotope composition and the diluent/sample ratio of the standard solution by a double-diluent method; secondly, mixing the calibrated standard solution with a standard substance composed of known isotopes according to different proportions, obtaining actual measurement data of the mixed sample through separation, purification and instrument test, mutually verifying the actual measurement data and simulated error data, and determining the optimal mixing range of the sample and the standard solution; and finally, mixing the calibrated standard solution with an unknown ultra-trace element sample in a suggested mixing range, performing separation and purification and double-diluent method instrument testing, and calculating by using a two-end-member isotope mixing model to obtain the isotope composition of the unknown sample. The invention provides a better choice for isotope analysis of low-content samples, and can obviously reduce the sample loading amount of the samples and buffer the interference of matrix elements.
Description
Technical Field
The invention belongs to the technical field of isotope geochemistry and analytical chemistry, and relates to a method for analyzing isotope composition of an ultra-trace element sample.
Background
In recent years, the application of unconventional stable isotope analysis in the fields of geology, celestial bodies, environment and the like has been deeply developed. Accurate measurement of the isotopic composition of a sample has become the basis and prerequisite for research in the above-mentioned disciplines. Two bottleneck problems facing current unconventional stable isotope analysis are: how to effectively reduce the sample concentration required by the analysis of an instrument and reduce the blank of the experimental process so as to reduce the sample loading amount of the sample. The former depends on the hardware condition of the instrument and the sample injection mode; the latter depends on laboratory cleanliness, reagent purity and pretreatment procedures. Updating instrument hardware can improve sensitivity and reduce the test concentration, but the ultra trace element sample often has stronger matrix effect and higher element interference, and the improvement of the sensitivity is accompanied by obvious matrix interference. The standard addition method is the most accurate test method for element content at present, and the matrix effect and the blank effect can be effectively inhibited by adding a standard substance with known composition into a sample. In isotope analysis, a learner combines a standard addition method and a standard-sample intersection method to analyze a trace element sample, but the accurate ratio of the standard addition method to the standard-sample intersection method cannot be effectively monitored, so that the data obtained by the method is poor in precision and insufficient in popularization.
Compared with a standard-sample intersection method and an element external standard method, the isotope double-diluent method can obtain the high-precision isotope ratio of a natural sample, and also can obtain the accurate diluent/sample ratio and the accurate element concentration. The method has higher tolerance on the recovery rate and the matrix effect of the purification process, and is suitable for analyzing low-content samples with complex matrixes. If the isotope double-diluent method is combined with the standard addition method, the proportion of the natural sample in the mixed sample can be accurately obtained through calculation, and the isotope data precision of the sample can be greatly improved. The isotope double-diluent-standard addition method disclosed by the invention obtains an optimal mixing proportion range through numerical simulation, and is consistent with measured data. The method can break through the lowest sample loading level determined by the current laboratory background and instrument hardware conditions, and effectively analyze the isotope composition of the ultra-trace element sample.
Disclosure of Invention
In order to solve the above-mentioned problems occurring in the prior art, the present invention provides a method for analyzing an isotopic composition of an ultra trace element sample. The technique is based on an isotope double diluent-standard addition method, and is characterized in that a known high diluent is mixed with a sample (diluted)The release agent/standard is P spk/std ) The standard solution of (2) is added with the sample to obtain the low diluent-to-sample ratio (diluent/(sample + standard) P spk/(std+spl) ) The isotope composition of the mixed solution and the accurate proportion of the diluent to the sample are tested, and the accurate isotope composition of the sample is calculated by utilizing a two-end-element isotope mixing model.
The invention provides a method for analyzing the isotopic composition of an ultra-trace element sample, which comprises the following steps:
the step 1 further comprises the following steps:
step 1.1, determining the optimal range of the proportion of a diluent and a sample according to the characteristics of a U-shaped error curve of an isotope double-diluent method;
step 1.2, preparing a standard solution with high diluent-to-sample ratio according to the range obtained in the step 1.1.
the step 2 further comprises: performing mass discrimination correction on the isotope ratio measured by the mass spectrometer by adopting a double-diluent bird nest iterative algorithm, and obtaining the accurate isotope composition of the standard solution and the ratio P of the diluent to the standard solution spk/std 。
the step 3 further comprises the following steps:
step 3.1, establishing the isotope composition of the sample and the isotope composition and diluent ratio (double diluent/(standard + sample), P) of the standard solution and the sample-standard mixed solution spk/(std+spl) ) The mathematical model relationship of (1);
step (ii) of3.2, simulating the ratio of different samples (f) in the mass spectrometry process by using the Monte-Carlo method according to the formula obtained in the step 3.1 spl ) Lower isotope composition (. delta.) spl ) An error increment value of (d);
step 3.3, consisting of an isotope (delta) spl ) Error of (d) and sample ratio (f) spl ) And (3) making a two-dimensional error curve graph as an object to obtain an optimal mixing range, wherein the stoichiometric parameters are sample proportion intervals corresponding to the range with the minimum error.
The step 4 further comprises the following steps:
step 4.1, based on the standard solution prepared in the step 1, taking the digested geological standard substance solution as a sample, and preparing different f from low to high spl A mixed sample of values;
step 4.2, actually measuring the mixed sample prepared in the step 4.1 on a mass spectrometer, obtaining real data of the mixed sample according to a double-diluent method, and calculating through a two-end isotope mixing model to obtain an accurate series f spl And delta spl A value; will calculate the series delta spl The value is compared with the recommended value and then verified with the simulation result obtained in step 3 to determine a reliable mixing range.
In the step 5, when the accurately calibrated standard solution is mixed with the unknown ultra trace element sample, because the concentration test of the unknown sample has errors, a proper sample proportion is usually selected, and the occurrence of the proportion of the edge sample is avoided. Meanwhile, for relatively reliable accuracy, the number of analyses is preferably 3 to 5.
The isotope double-diluent-standard addition method provided by the invention provides a method for analyzing the isotope composition of an ultra-trace element sample, which is simple and quick to operate, breaks through the lowest sample loading amount determined by the background level of a laboratory, and enables a mixed sample to have a lower proportion of interference elements and matrix elements compared with an original sample due to the standard addition, so that a separation and purification method has more choices. The invention breaks through the limit of the sample loading amount required by isotope analysis, expands the sample range of isotope analysis, and greatly promotes the application of isotope analysis technology in multiple research fields of geology, astronomy, environment, ecology and the like.
Drawings
FIG. 1 is a flow chart of the present invention.
FIG. 2 is a schematic diagram showing the simulation error of Cd isotope by Monte-Carlo method in the example;
FIG. 3 is a schematic diagram showing the simulation error of Mo isotope in the example by Monte-Carlo method;
FIG. 4 is a graph of the error of isotope analysis of samples at different ratios and the ratio of diluent to sample in the examples;
FIG. 5 shows the Cd isotope test result of the geological standard NIST SRM 2711a in the example;
FIG. 6 shows the Mo isotope test results of the geological standard NOD-P-1 in the examples.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments and the accompanying drawings.
The invention provides a method for analyzing isotope composition of an ultra-trace element sample, which is suitable for all elements (the number of stable isotopes is more than or equal to 4) which can be analyzed by using an isotope double-diluent technology in a periodic table.
Fig. 1 is a flow chart of a method for analyzing the isotopic composition of an ultra trace element sample according to the present invention, which is described below based on an isotopic double-diluent method and a standard addition method, taking Cd and Mo as an example, and as shown in fig. 1, the method comprising the steps of:
the step 1 further comprises the following steps:
step 1.1, determining the optimal range of the sample/diluent ratio by a double-diluent method;
after the double diluents are selected, a U-shaped change relationship exists between the ratio of the diluents to the samples and errors introduced by a double diluent method, and large errors are introduced when the diluents are too high and too low, so that the accuracy and precision of the samples are poor, therefore, the ratio of the diluents to the samples is kept within a certain range, the accuracy and precision of the samples within the range are guaranteed to be optimal, and the range is called normal spike before. Below this ratio is called under spike and above this ratio is called over spike. To be provided with 111 Cd- 113 The double diluent of Cd is taken as an example, 111 Cd spike / 112 Cd sample (P spk/spl ) The optimal range is 0.8-6.0, and the optimal ratio is 2.0. For the 97 Mo- 100 A Mo double-diluent agent, wherein the Mo double-diluent agent, 100 Mo spike / 98 Mo sample (P spk/spl ) The optimal range is 1.2-8.0, and the optimal ratio is 2.75.
And step 1.2, preparing a standard solution according to the optimal proportion range obtained in the step 1.1.
The preparation of the standard solution preferentially selects pure and high-concentration single element standard solution; and separating and purifying the second highest concentration natural sample to prepare a standard solution. NIST SRM 3108, Munster Cd, BAM-I012 and Spex Cd are the most common Cd isotope standard solutions, the isotope composition of which is accurately determined by different laboratories on the world, and are suitable for preparing the secondary standard solutions required by people. If positive delta is required 114/110 The Cd value of the solution can be mixed with Hunster Cd by NIST SRM 3108; if negative delta is required 114/110 Cd value of the solution can be determined by NIST SRM 3108BAM-I012 or Spex Cd. Due to the fact that 111 Cd spike / 112 Cd sample The optimal ratio of (A) to (B) is 2, and when the standard solution is prepared, 111 Cd spike / 112 Cd sample selected to be around 4.0. Mixing the standard solution to which the double diluent has been added with the sample 111 Cd spike / 112 Cd sample Will fall within the range of 0-4.0 and, when the sample proportion is 50%, 111 Cd spike / 112 Cd sample approximately 2.0. For analysis of low sample content, the sample fraction is usually as low as possible to reduce the loading of the actual sample, typically below 50%. That is, of the final mixed solution 111 Cd spike / 112 Cd sample Mainly in the range of 2.0-4.0. In the same way, according to the double dilution error curve of Mo, the Mo standard solution is prepared 100 Mo spike / 98 Mo sample The value is chosen to be around 5.5.
wherein
And
the isotope ratios of the standard solutions with double diluent and without diluent are shown respectively.
3, simulating by using a Monte-Carlo method to obtain errors introduced in the mass spectrometry process of different sample proportions based on mass spectrometer hardware parameters and the prepared standard solution isotope composition, and obtaining preliminary proportioning parameters;
the step 3 further comprises the following steps:
and 3.1, establishing the relation between the isotope composition of the sample and the standard solution, the isotope composition of the mixed solution and the proportion of the diluent and the sample according to the two-end element isotope mixing model. Taking Cd isotope as an example, the isotope composition (delta) of the standard solution 114/110 Cd and diluent ratio ( 111 Cd spk / 112 Cd std ) Are respectively marked as delta std And P std Isotopic composition (delta) of the mixed solution after sample addition 114/110 Cd and diluent ratio ( 111 Cd spk / 112 Cd std+spl ) Are respectively marked as delta mix And P mix Then, then
111 Cd spk / 112 Cd std ＝P std (4)
111 Cd spk / 112 Cd std+spl ＝P mix (5)
Combine the formulas (4) and (5) to obtain
112 Cd std / 112 Cd std+spl ＝P mix /P std (6)
Assuming that the Cd content of the sample in the mixed solution is f spl The standard solution is in the ratio of f std True delta of the sample 114/110 Cd value of delta spl According to the isotope two-end-element mixture model has
f spl +f std ＝1 (7)
δ mix ＝f spl *δ spl +f std *δ std (8)
Combining (6) and (7) to obtain
f std ＝Cd std /Cd std+spl ＝ 112 Cd std / 112 Cd std+spl ＝P mix /P std (9)
f spl ＝1-f std ＝1-P mix /P std (10)
By substituting the formulae (9) and (10) into the formula (8)
δ spl ＝(P std *δ mix -P mix *δ std )/(P std -P mix ) (11)
And 3.2, simulating errors introduced in the mass spectrometry process of the sample-standard mixed solution under different sample proportions by using a Monte-Carlo method according to the formula obtained in the step 3.1, and preliminarily obtaining the proportioning parameters of the sample and the standard solution. The Monte-Carlo method principle is that a group of uniformly distributed data is converted into a group of normally distributed data, and according to the previous research, the data in the isotope determination process of the mass spectrometer follows the normally distributed data, so that the measured value of the instrument can be simulated according to the characteristic parameters of the instrument and the Monte-Carlo method. Finally, combining the formulas in the step 3.1, and calculating the sample proportion and the isotope composition error based on each group of simulation data;
step 3.3, consisting of an isotope (delta) spl ) Error of (d) and sample ratio (f) spl ) And (3) making a two-dimensional error curve diagram as an object, wherein the ideal proportioning parameter, namely the range with the minimum error, corresponds to the optimal sample proportion interval.
In this step, with f spl As abscissa, isotopic composition (delta) spl ) The two-fold standard deviation (2SD) is the ordinate, and a two-dimensional error curve graph is prepared, as shown in fig. 2 and 3, fig. 2 is a two-dimensional curve graph of the error of the Cd isotope composition and the sample ratio, and fig. 3 is a two-dimensional curve graph of the error of the Mo isotope composition and the sample ratio. As can be seen from the figure, the error curves of both Cd isotope and Mo isotope present a "U-shaped" characteristic, i.e. when the sample proportion is too high or the standard solution proportion is too high, the error will become large rapidly. In view of the need for low sample analysis, a moderately low sample fraction, i.e., 20% to 50% should be selected in practice.
the step 4 further comprises the following steps:
step 4.1, based on the standard solution prepared in the step 1, taking the digested geological standard substance solution as a sample, and preparing different sample ratios (f) from low to high spl ) The mixed sample of (1);
step 4.2 preparation of step 4.1After the mixed sample is separated and purified, the isotope composition and the diluent/sample ratio of the mixed sample are obtained by testing on a mass spectrometer by using a double-diluent method, and then the accurate sample proportion and isotope composition are obtained by calculating through a two-end-member isotope mixing model. With f spl As abscissa, isotopic composition (delta) spl ) The error (2SD) of (1) is a vertical coordinate, and a two-dimensional error curve diagram is drawn, as shown in fig. 4, and fig. 4 is a two-dimensional curve diagram of error-sample ratio of actually measured geological standard substance Cd isotope composition. And (4) mutually verifying the simulation result obtained in the step (3) to determine the optimal sample proportion range.
And 5, mixing the sample proportion range obtained in the step 4 with the accurately calibrated standard solution, and calculating by testing the isotope composition of the mixed sample and the diluent/sample ratio to obtain the isotope composition of the unknown sample.
In this step, when analyzing the actual sample, because the concentration test of the unknown low-content sample has an error, a moderate sample proportion is usually selected, and the occurrence of the marginal sample proportion is avoided. Also, for relatively reliable accuracy, 3-5 analyses are preferred. As shown in FIGS. 5 and 6, FIG. 5 is a graph showing the result of testing the Cd isotope composition of the international geological standard substance soil NIST 2711a by the method, and FIG. 6 is a graph showing the result of testing the Mo isotope composition of the international geological standard substance manganese nodule NOD-P-1 by the method. The grey shading in both figures represents the long-term accuracy. As can be seen from the two figures, the method is effective for analyzing the samples of Cd isotope and Mo isotope for a long time and has reliable precision.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A method for analyzing the isotopic composition of an ultra trace element sample, comprising the steps of:
step 1, preparing a standard solution with high diluent/sample proportion according to the characteristic of a U-shaped error curve of an isotope double-diluent method, wherein the diluent/standard is P spk/std ；
Step 2, accurately calibrating the isotope composition of the standard solution and the proportion of the isotope composition to the diluent by using a double diluent method on a multi-receiving cup inductively coupled plasma mass spectrometer;
step 3, simulating by using a Monte-Carlo method to obtain errors introduced by the sample-standard mixed solution in the mass spectrometry process under different sample proportions, and preliminarily obtaining mixed proportioning parameters of the sample and the standard solution;
step 4, mixing the calibrated standard solution with geological standard substances composed of known isotopes according to different proportions, obtaining actual measurement data of the mixed sample through separation and purification and mass spectrometry, verifying the actual measurement data with the error data simulated in the step 3, and determining the optimal mixing range of the sample and the standard solution, wherein the sample/(sample + standard solution) is f spl ；
And 5, mixing the accurately calibrated standard solution and the unknown ultra-trace element sample in the optimal mixing range based on the optimal mixing range obtained in the step 4, testing the isotope composition of the mixed sample and the ratio of the diluent to the sample by a double-diluent method, and calculating to obtain the isotope composition of the unknown sample by a two-end isotope mixing model.
2. The method for analyzing the isotopic composition of an ultra trace element sample according to claim 1, wherein said step 1 comprises the steps of:
step 1.1, determining the optimal range of the sample/diluent ratio of the double-diluent method according to the characteristics of a U-shaped error curve of the isotope double-diluent method;
and 1.2, preparing a high-proportion standard solution of the diluent and the sample within an optimized range according to the range obtained in the step 1.1.
3. The method of claim 1, wherein the method comprises analyzing the isotopic composition of the ultra trace element sampleIn that, the step 2 includes: performing mass discrimination correction on the isotope ratio measured by the mass spectrometer by adopting a double-diluent bird nest iterative algorithm, and obtaining the accurate isotope composition of the standard solution and the ratio P of the diluent to the sample spk/std 。
4. The method for analyzing the isotopic composition of an ultra trace element sample according to claim 1, wherein said step 3 comprises the steps of:
step 3.1, establishing a mathematical model of the isotope composition of the sample and the standard solution, the isotope composition of the sample-standard mixed solution and the proportion of the diluent and the sample, wherein the diluent/(standard + sample) is P spk/(std+spl) ；
Step 3.2, according to the formula obtained in the step 3.1, simulating the mass spectrometry process by using the Monte-Carlo method, wherein the ratio f of different samples is spl Lower sample isotopic composition delta spl An error increment value of (d);
step 3.3, isotopically forming delta spl Error of (2) and sample fraction f spl And (3) making a two-dimensional error curve graph as an object to obtain an optimal mixing range, wherein the stoichiometric parameters are sample proportion intervals corresponding to the minimum error range.
5. The method for analyzing the isotopic composition of an ultra trace element sample according to claim 1, wherein said step 4 comprises the steps of:
step 4.1, based on the standard solution prepared in the step 1, taking the digested geological standard substance solution as a sample, and preparing different f from low to high spl A mixed sample of values;
step 4.2, actually measuring the mixed sample prepared in the step 4.1 on a mass spectrometer, and calculating by using a double-diluent method according to actually measured data to obtain accurate f spl And delta spl A value; and (4) comparing the calculated isotope composition of the geological standard substance with a recommended value, and mutually verifying the isotope composition with the simulation result obtained in the step (3) to determine the optimal sample proportion range.
6. The method according to claim 1, wherein in the step 5, the precisely calibrated standard solution is mixed with the unknown ultra trace element sample, and the mixture is subjected to separation and purification and double-diluent method instrument testing, analyzed for 3-5 times, and then the precise and high-precision isotope composition of the unknown sample is calculated through a two-terminal isotope mixing model.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210447863.8A CN114813904A (en) | 2022-04-26 | 2022-04-26 | Method for analyzing isotope composition of ultra-trace element sample |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210447863.8A CN114813904A (en) | 2022-04-26 | 2022-04-26 | Method for analyzing isotope composition of ultra-trace element sample |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114813904A true CN114813904A (en) | 2022-07-29 |
Family
ID=82508005
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210447863.8A Pending CN114813904A (en) | 2022-04-26 | 2022-04-26 | Method for analyzing isotope composition of ultra-trace element sample |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114813904A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118130598A (en) * | 2024-04-30 | 2024-06-04 | 云南商测质量检验技术服务有限公司 | Method and system for measuring sulfur dioxide in food |
-
2022
- 2022-04-26 CN CN202210447863.8A patent/CN114813904A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118130598A (en) * | 2024-04-30 | 2024-06-04 | 云南商测质量检验技术服务有限公司 | Method and system for measuring sulfur dioxide in food |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Prosser et al. | High-precision determination of 2H/1H in H2 and H2O by continuous-flow isotope ratio mass spectrometry | |
| Schaltegger et al. | Long-term repeatability and interlaboratory reproducibility of high-precision ID-TIMS U–Pb geochronology | |
| CN103226128B (en) | Method for analyzing source of secondary organic carbon in ambient air fine particles | |
| Haley et al. | Development of a flow-through system for cleaning and dissolving foraminiferal tests | |
| CN111141812A (en) | U-Pb dating data correcting method, storage medium and correcting equipment for sphene | |
| CN114813904A (en) | Method for analyzing isotope composition of ultra-trace element sample | |
| Shalev et al. | Precise determination of δ 88/86 Sr in natural samples by double-spike MC-ICP-MS and its TIMS verification | |
| CN105510427A (en) | Numerical treatment method for multi-element isotope double spike technology | |
| Dede | A case study for measurement uncertainty of heavy metal analysis in drinking water with inductively coupled plasma-mass spectrometry (ICP-MS) | |
| JP4434026B2 (en) | Isotope ratio analysis method using plasma ion source mass spectrometer | |
| Seth et al. | Accurate measurements of Th–U isotope ratios for carbonate geochronology using MC-ICP-MS | |
| Sakai | Routine soil analysis using an Agilent 8800 ICP-QQQ | |
| Meijer et al. | High-accuracy 14C measurements for atmospheric CO2 samples by AMS | |
| CN108931590B (en) | Correction method for multi-batch targeted metabonomics data | |
| Geertjens et al. | Straightforward model construction and analysis of multicomponent biomolecular systems in equilibrium | |
| CN108827750B (en) | Isotope dilution quantitative detection method | |
| CN112345680B (en) | Method for simultaneously detecting eight sterols in ganoderma lucidum | |
| Hill-Pearce et al. | Characterisation of gas reference materials for underpinning atmospheric measurements of stable isotopes of nitrous oxide | |
| Bodorkos et al. | Best of both worlds: combining SHRIMP and CA-TIMS methods in refining geochronological determinations for timescale calibration | |
| CN117723623B (en) | Source analysis method for subdividing secondary organic aerosol by combining contributions of organic matters in inorganic matrix | |
| Lim et al. | Isotope ratios of total C, N, and S in particulate matter simultaneously calibrated by mixed USGS and IAEA reference materials | |
| Martins et al. | Stable isotopes of oxygen and hydrogen in water: analytical method evaluation and the determination of δ18O and δ2H on a control sample | |
| Grannis | Studies of the reliability of constituent target values established in a large inter-laboratory survey. | |
| CN117686474B (en) | Uranium concentration measurement analysis method | |
| Sloop | Non-Traditional Calibration Strategies for Applications in Atomic Spectrometry |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |