Total Evaporation Method Research Articles

ANALYSIS OF CHEMICAL CONTENTS IN RAW MATERIAL OF RICH MINERALS SEA SALT

The mineral content of seawater is a natural raw material to produce rich mineral sea salt. Rich mineral sea salt is a consumption salt with a NaCl content of <50% used to live a low sodium diet for a healthy lifestyle. In general, traditional sea salt was produced with the multistage evaporation method to obtain a NaCl content of ≥ 94.7%, whereas the production of rich mineral sea salt uses a total evaporation method and then removes the salt flower at a certain concentration to get low sodium chlorine and contain other natural minerals. This study aims to analyze the chemical content of the raw material of rich mineral sea salt. The location of seawater used as raw material for rich mineral sea salt is Camplong District, Sampang Regency. Samples were obtained from sea level with a distance of ± 400 m from the coastline and carried out during high tide conditions. The chemical analysis of seawater samples consists of Na, Mg, Ca, K, Fe, Cl− dan SO42−. The analysis method is based on the Indonesian National Standard of environmental quality test. The results of the major mineral analysis showed that the largest mineral content of seawater was calcium (Ca2+) at 492.350±10.395 mg/L and Sodium (Na+) at 482,000±1.979 mg/L. In contrast, the smallest mineral content is iron mineral (Fe2+) of < 0.08 mg/L. These results will be used for preliminary data before producing naturally rich mineral sea salt.

A combined TIMS and ICP-MS study for Th0.5Np0.5O2 thorium neptunium mixed oxide analysis

This paper presented thorium and neptunium quantification of a new synthesized powder, a (Th,Np)O2 mixed oxide. Thorium was quantified by Thermal Ionization Mass Spectrometry using Isotope Dilution (ID-TIMS) which is one of the most accurate methodology to determine actinide mass fraction. The (sample-spike) mixture isotope ratio was measured using the TIMS reference method for major isotope ratio determination, i.e. the total evaporation method. An expanded uncertainty below 1% was estimated for the Th mass fraction. The study of the uncertainty sources showed that the main one comes from the spike mass fraction uncertainty. As Np quantification with ID-TIMS is difficult due to the lack of commercially-available spike solution, the Np mass fraction was obtained by ICP-MS measurements using a gravimetric standard addition method combined with an analytical internal standard. The developed method used an element initially present in the sample, here Th, as an internal standard for ICP-MS measurements. This helps reducing the number of manipulation as well as cross contamination, which is an important risk when experiments are performed in glove boxes. Also, equations are simplified. An expected uncertainty about 1.8% was estimated for Np. Finally, the Th–Np mixed oxide was found to have a Th0.4836(50)Np0.5164(50)O2 stoichiometry. This study can be extended to other complicated samples or to the characterization of in-house certified reference material.

Isotope Dilution-Total Evaporation-Thermal Ionization Mass Spectrometric Direct Determination of Radioactive Strontium-90 in Microdrop Samples.

Thermal ionization mass spectrometry (TIMS) was used to directly quantify an ultratrace of radioactive 90Sr in microliter droplet samples. No chemical separation was required in removing isobaric interferences on M = 90 such as 90Zr and organic molecules in the mass spectrum because the difference in evaporation and ionization (emission) temperature among organic molecules, Zr and Sr, allows us to control the emission manner and significantly suppress the isobaric interferences. Direct quantification was achieved by improving the intercalibration of Faraday cups and ion counting in an isotope dilution (ID) method. Furthermore, the use of a total evaporation method (TE) enhanced the detection efficiency by the complete collection of the 90Sr ion beam from the samples and minimized the complexity of the fractionation effect in the isotope ratio calculation. In this study, 1 fg of 90Sr (equal to activity of 5 millibecquerel (mBq)) in a very low-volume sample with 108 times greater isobaric interference from 90Zr was successfully measured using the proposed ID-TE-TIMS method. The limit of detection was 0.029 fg (equal to 0.15 mBq) without any preconcentration. To demonstrate the wide usability of this method, low-volume samples of tears, eyelashes, saliva, environmental standards, and water samples (i.e., seawater and ground water) were analyzed within 1 h. The relationship of the measured values between this ID-TE-TIMS method and a radiometric analysis was shown to have good linearity.

Development and comparison of high accuracy thermal ionization mass spectrometry methods for uranium isotope ratios determination in nuclear fuel

This study presents the development and the comparison of high accuracy methods for uranium isotope determination by thermal ionization mass spectrometry. Two methods for uranium minor isotope ratio determination were compared in term of accuracy, analysable quantity, analysis time and versatility: the total evaporation and the classical method with multi-dynamic sequences. The mathematical correction of the abundance sensitivity and the detector calibration within the classical method helps decreasing the uncertainties and the biases compared to the total evaporation method. This comparative study was conducted within the framework of the “2017 Nuclear Material Round Robin” participation organized by the International Atomic Energy Agency.

Preparation and certification of the uranium nitrate solution reference materials series IRMM-2019 to IRMM-2029 for the isotopic composition

The IRMM-2019-2029 series of uranium nitrate solutions was certified for the isotopic composition. The solutions were originally prepared for the certification of the IRMM-019-029 series of uranium hexafluoride (UF6) materials in 2014, for which certification measurements were performed by thermal ionization mass spectrometry after conversion of UF6 into uranyl nitrate solutions. Analyses were performed using the modified total evaporation method and for some materials with low 236U abundances, the n(235U)/n(238U) ratio was measured using a n(233U)/n(236U) double spike. The integrity of the certified values after dilution and ampouling of the original solutions was checked through process control measurements.

Americium isotope analysis by Thermal Ionization Mass Spectrometry using the total evaporation method

In this paper, a simple analytical procedure was developed to measure americium isotope ratios and concentration with high accuracy. The method was tested during the participation in a round robin test organized by the Analytical Methods Committee of the French Atomic Energy Commission. The measurements were performed by Thermal Ionization Mass Spectrometry using the total evaporation method, which is a reference technique for determining actinide isotopic compositions. Expanded uncertainties were estimated at 0.1% and 0.8% for the 241Am/243Am isotope ratio and the Am concentration, respectively. Compared to the assigned value, biases below 0.0001% and 0.02% were calculated for the 241Am/243Am isotope ratio and the Am concentration, respectively.

A multiple ion counter total evaporation (MICTE) method for precise analysis of plutonium by thermal ionization mass spectrometry

This paper presents a total evaporation method for the analysis of sub-picogram quantities of Pu, utilizing an array of multiple ion counters. Data from three standards are presented to assess the utility of the technique. An external precision of 1.5% RSD (2σ) was achieved on aliquots approaching 100 fg for the minor 240Pu isotope. Accurate analysis of <1 femtogram of 240Pu, is achievable, with an external reproducibility of better than 10% RSD (2σ). This new technique represents a significant advance in the total evaporation method and will allow routine measurement of femtogram sized Pu samples by thermal ionization mass spectrometry.

Static, Mixed-Array Total Evaporation for Improved Quantitation of Plutonium Minor Isotopes in Small Samples.

Actinide isotope measurements are a critical signature capability in the modern nuclear forensics "toolbox", especially when interrogating anthropogenic constituents in real-world scenarios. Unfortunately, established methodologies, such as traditional total evaporation via thermal ionization mass spectrometry, struggle to confidently measure low abundance isotope ratios (<10(-6)) within already limited quantities of sample. Herein, we investigate the application of static, mixed array total evaporation techniques as a straightforward means of improving plutonium minor isotope measurements, which have been resistant to enhancement in recent years because of elevated radiologic concerns. Results are presented for small sample (~20ng) applications involving a well-known plutonium isotope reference material, CRM-126a, and compared with traditional total evaporation methods. Graphical Abstract ᅟ.

Development of an analysis method of minor uranium isotope ratio measurements using electron multipliers in Thermal Ionization Mass Spectrometry

A simple analytical procedure was developed to measure with high accuracy the isotope ratio of minor isotope of natural uranium present in small quantities using a thermal ionization mass spectrometer (TIMS). The reduction of quantities used for analysis and the measurement of non-abundant isotopes are of prime interest in the nuclear industry. Indeed it is necessary to reduce the analyst received dose and the effluent released, as well as realizing measurement at trace level. The new generation of TIMS is equipped with a multicollection system of electron multipliers: discrete dynode electron multiplier (SEM) and continuous dynode electron multiplier (MIC), that improve the sensitivity compared to faraday cups. The procedure developed was verified using Certified Reference Material IRMM 052. Results were evaluated relying on NF T 90-210 norm regarding method validation. First, the isotope ratio 234U/238U was examined by total evaporation using the SEM and MIC to measure 234U and the faraday cup to measure 238U. In a second approach, the isotope ratio 235U/238U was studied by total evaporation using the SEM to measure 235U and the faraday cup to measure 238U. The classical method with peak-jumping SEM measurement was also used. Total evaporation method employing only the faraday cup was used to confront the results obtained. The analyzable quantity was reduced from 250ng to 50ng for the 235U/238U isotope ratio and from 1270ng to 50ng for the 234U/238U isotope ratio with acceptable uncertainties thanks to the use of electron multipliers. For all experiments were the accuracy was achieved, the calculated uncertainties were below to 0.28% for the 235U/238U isotope ratio and 5% for the 234U/238U isotope ratio.

Studies on the effects of cucurbit (n = 7) uril on the physicohemical properties and anticancer activity of 10-hydroxycamptothecin

The changes in the physicochemical properties and the anticancer activity of 10-Hydroxycamptothecin (HCPT) in the presence of Cucurbit (n = 7) uril(Q[7]) were studied by using UV absorption spectroscopy, fluorescence spectroscopy and phase solubility method. The results revealed that in the acid solution (pH 2), the absorption band of the guest HCPT exhibited a progressively lower absorbance at λ265 nm, while a progressively higher absorbance at λ425 nm as the ratio of N(Q[7])/N(HCPT) was increased. A sharp isosbestic point at λ387 nm was consistent with a simple interaction between Q[7] and HCPT. The emission spectra of the guest HCPT also exhibited a progressive decrease in fluorescence intensity at λ558 nm with a violet shift when the ratio of N(Q[7])/N(HCPT) was increased. The measured data from both absorption spectrophotometric and fluorescence spectroscopy analysis fitted to a 2 : 1 host:guest complexation, yielded a calculated stable constants (β) of 1.549 x 10(13) L2 x mol(-2) and 0.907 x 10(13) L2 x mol(-2) respectively through Reactlab EQULLIBRIA software. The effect of Q[7] on the solubility of HCPT was investigated by using phase solubility method. Upon the addition of Q[7] concentration, the solubility of HCPT was enhanced step by step at the value of pH 2 and an about 250 times advance was attained when the concentration of Q[7] was 1 x 10(-3) mol x L(-1), while the Q[7]-HCPT inclusion complex made by total evaporation method can increase about 1 170 times compared to the pure HCPT. At the end, the mixtures of Q[7] and HCPT were tested in terms of cytotoxicity on the human lung cancer cell line A549 and human leukemia cell line K562 to compare their reactivity with the free HCPT and the comparative cytotoxic activity was got for A549 and K562.

Re-certification of the CRM 125-A UO2 fuel pellet standard for uranium isotopic composition

The U.S. Department of Energy New Brunswick Laboratory (NBL) has been tasked to develop certified reference materials (CRMs) tailored for the demands of modern analytical methods in the field of nuclear forensics. As part of this effort, several existing uranium CRMs are being characterized for additional attributes. One of these materials is the CRM 125-A uranium oxide (UO2) pellet assay and isotopic standard (4% enriched in 235U), which is being developed as a CRM for U–Th age determinations. Reliable U isotopic composition data with relatively small uncertainties are essential for use as a uranium age standard. Therefore, re-characterization of the uranium isotopic composition of CRM 125-A was deemed necessary due to poorly constrained minor U abundances (i.e., 234U and 236U) resulting from instrumental limitations of the mass spectrometer used at the time of original certification (1996–1997). The analytical work presented in this study was undertaken with the purpose of reducing the uncertainties of certificate values for uranium isotope-amount ratios.Six randomly selected CRM 125-A pellets were characterized for the uranium isotopic abundances by thermal ionization mass spectrometry (TIMS). The re-certified major ratio n(235U)/n(238U) of 0.042301(25) was determined using the total evaporation (TE) and modified total evaporation (MTE) methods. The re-certified minor isotope ratios n(234U)/n(238U) and n(236U)/n(238U) of 0.00039130(38) and 0.0000040754(47), respectively, were measured by MTE and a conventional Faraday cup analysis method using internal normalization. Additionally, the material was checked for the presence of 233U using a secondary electron multiplier (SEM) equipped with a retarding potential quadrupole (RPQ). No 233U was observed within the instrumental detection limit. The homogeneity of CRM 125-A was confirmed by the absence of any statistically significant unit-to-unit variation in the uranium isotope amount ratios. The new values measured in this study represent a considerable refinement of the older data, in particular for the minor ratios, with uncertainties that are significantly smaller than those cited in the original certificate. The results of the characterization analyses are presented along with an explanation of the uncertainty estimates, which are compliant with the Guide to the Expression of Uncertainty in Measurement (GUM).

Total evaporation method for uranium isotope-amount ratio measurements

Total evaporation (TE) is an analysis technique for the measurement of uranium isotopic abundance ratios using thermal ionization mass spectrometry (TIMS). A small mass dependent bias observed in this analytical technique is determined by an external correction factor using well characterized standards (most often certified reference materials, CRMs). The technique had been demonstrated to be highly precise and accurate for major isotope-amount ratio measurements of uranium and plutonium. We compare the performance of the TE analytical technique for uranium isotope ratio measurements on two TIMS instruments (TRITON and MAT261) using well characterized CRMs from NBL and investigate the dependence of the instrumental mass bias on the amount of sample analyzed. It is concluded that the mass bias during a TIMS uranium isotopic analysis by TE is independent of the amount of material analyzed. Unlike the major ratio, minor isotope ratio measurements by TE are biased high due to peak-tailing from the major isotopes. The biases in the minor isotope ratio data using TE are evaluated using well characterized NBL CRMs.

The direct total evaporation (DTE) method for TIMS analysis

The total evaporation (TE) method is an established analytical method for safeguards measurements of uranium and plutonium isotope-amount ratios using thermal ionization mass spectrometry. As fractionation effects are minimized in this analytical method, it is a method of choice in many practical applications that require high accuracy and precision isotope abundance ratio measurements. The speed of signal regulation is a critical parameter for a steady sample evaporation process. Standard TE methods use the data system to read the ion signal and its difference from the target intensity is used to determine the increment in which the filament is heated. The new, hardware-driven proprietary direct total evaporation method uses an analog regulator in the filament power supply with direct feedback of the detector intensity. Only target values are set by the data system initially. The filament heating and sample evaporation process is then carried out by the hardware. The data system just monitors, collects, and calculates the data. Due to the nature of electronic regulation the ion signal is kept stable for the duration of the run until the whole sample is consumed. For routine uranium isotopic analyses of the major isotope-amount ratio n(235U)/n(238U) using a modified MAT261 instrument with SPECTROMAT™ hardware and software upgrades, precision (relative standard deviation, expressed as a percent) and accuracy (relative difference, expressed as a percent) of 0.05 % are obtained for low enriched and high enriched uranium certified reference materials.

Uranium isotope abundance ratios in natural uranium metal certified reference material 112-A

Certified reference material (CRM) 112-A, uranium metal assay standard, with “natural” U isotopic composition and CRM 145, uranium assay standard solution made by dissolving CRM 112-A metal were analyzed using TRITON Thermal Ionization Mass Spectrometer (TIMS) to characterize the uranium isotopic abundances. The certified 235U/238U “major” ratio of 0.0072543 (40) in CRM C112-A and CRM 145 is determined using the total evaporation (TE) and modified total evaporation (MTE) methods. In the MTE method, the total evaporation process is interrupted on a regular basis to allow correction of background from peak tailing, internal calibration of the secondary electron multiplier (SEM) detector versus the Faraday cups, peak-centering, and ion source re-focusing. For the “minor”234U/238U and 236U/238U ratio measurements using MTE, better precision and accuracy are achieved compared to the TE analyses. The certified 234U/238U ratio of 0.000052841 (82) in CRM C112-A and CRM 145 is determined using a conventional analysis technique that incorporates an internal mass bias correction utilizing the measured 235U/238U ratio and correction for peak tailing from 235U and 238U. The 236U/238U isotope abundance ratio in CRM C112-A and CRM 145 is estimated to be <5×10−9. The CRM 112-A and CRM 145 materials show no evidence for any statistically significant unit-to-unit variations in uranium isotope abundance ratios. The homogeneity of both CRMs is established. The measurements leading to the certification of uranium isotopic abundances are discussed.

Comparison of NBL CRM 112-A and Ampoulated Uranyl Nitrate Solution by TIMS Analysis: Initial Verification of a Potential Normal Uranium Isotope-Amount Ratio Reference Material

An ampoulated uranyl nitrate solution has been compared with NBL CRM 112-A for isotopic-amount ratios as initial verification work for a future mass spectrometry-specific Normal Uranium (NU) reference material. Randomly selected ampoules of the NU solution were analyzed to assess homogeneity of the production run. The comparison analyses were performed by TIMS using Total Evaporation (TE) and Modified Total Evaporation (MTE) methods. No difference was found for the n(235U)/n(238U) and n(234U)/n(238U) isotope-amount ratios between the NU solution and the CRM 112-A material. Moreover, the NU solutions appear to be isotopically homogenous with no statistically significant unit-to-unit difference observed.

Uranium and plutonium analysis of nuclear material samples by multi-collector thermal ionisation mass spectrometry: Quality control, measurement uncertainty, and metrological traceability

Metrological studies and recent improvements in multi-collector thermal ionisation mass spectrometry (MC-TIMS) of uranium and plutonium in bulk nuclear material samples are presented with a focus on nuclear safeguards. Using total evaporation and modified total evaporation methods, experimental data are presented for isotope ratio measurements in routine mode spanning a range of almost ten orders of magnitude, with n(U-236)/ n(U-238) measurements as low as a few parts per billion. Based upon these data, measurement reproducibility, associated measurement uncertainties with comparison to International Target Values (ITV), an upper limit of the instrumental uranium memory effect and of the hydride formation, and process and instrumental blank levels are examined. A comparison of measurement performance between the latest and previous generation of instruments for the total evaporation method is conducted. In addition, the implementation of a quality control procedure including control charts is presented and, in this context, commercially available U or Pu certified reference materials for isotope ratio and isotope dilution mass spectrometry are surveyed. The implementation of the Guide to the expression of Uncertainty in Measurement (GUM) is discussed for the modified total evaporation method. To address the importance of metrological traceability of measurement results to the SI units, the agreement between the certified values of two independently produced series of uranium certified reference materials (CRMs) – NBL and IRMM U series – is probed. Using IRMM CRMs as calibration standards, a new set of values for selected NBL U series CRMs is presented with expanded uncertainties of about 0.035% for major isotope ratios and at an order of magnitude of 0.1–0.5% for minor ratios.

The use of total evaporation method using Channeltron electron multipliers by thermal ionization mass spectrometry for europium isotope ratio measurements on picogram sample amounts

Thermal ionization mass spectrometry (TIMS) is a well established instrumental technique for providing accurate and precise isotope ratio measurements for elements with low first ionization potential. In the nuclear domain, particularly for the study of spent nuclear fuel sample solutions, the reduction of quantities is an important issue in order to decrease the analyst exposition to the radioactive samples. This paper presents experimental results obtained for picogram quantities of samples using electron multipliers (Channeltrons) implanted on the new generation of TIMS associated with the total evaporation (TE) acquisition method. TE method presents some advantages for the measurement of low quantities of samples in relation to the whole sample consumption and the integration of the whole signal. For this study, a Thermal Ionization Mass Spectrometer from IsotopX (Isoprobe-T) equipped with a multi-collector system including Faraday cups and four movable Channeltrons is used. This work is focused on lanthanide elements, and particularly europium, in relation to the importance of their characterization in the spent fuel to validate neutronic calculation codes. In a first approach, europium isotopic ratios by total evaporation method using Faraday cups are obtained for quantities down to 250 pg. The results obtained by TE (Faraday cups only) on such low quantities confirm the potentialities of the method. A reproducibility of 2.5‰ ( k = 2), was obtained on the 153Eu/ 151Eu ratio ( n = 11), for natural samples with an accuracy around 1‰. In a second approach the same procedure is tested on Channeltron detectors by reducing the amounts of samples (from 50 pg to 1 pg). In order to obtain accurate isotope results, intrinsic parameters such as applied voltages, dead time and noise were determined. A Channeltron specific intercalibration gain method was also developed, as this parameter was found to be the major source of uncertainties using this type of detectors. The reproducibility on the 153Eu/ 151Eu ratio was respectively found around 3% ( k = 2). These results show the potentialities of isotopic measurements of sub-nanograms quantities and the different sources of uncertainties using total evaporation and Channeltrons on the Isoprobe-T.

IRMM-3100a: A new certified isotopic reference material with equal abundances of 233U, 235U, 236U and 238U

The new so-called Quad-IRM (“Quadruple Isotope Reference Material”) was prepared from highly enriched 233U, 235U, 236U and 238U isotopic materials using an optimized combination of gravimetrical mixing and mass spectrometry. Within the mixing process the isotope ratios were adjusted to about n( 233U)/ n( 235U)/ n( 236U)/ n( 238U) = 1/1/1/1 and certified with expanded relative uncertainties of 0.0054% per mass unit (coverage factor k = 2). This new isotope reference material is ideal for verifying the inter-calibration of multi-detector systems in isotope mass spectrometry. The certified n( 233U)/ n( 236U) ratio of IRMM-3100a was derived from the mass metrology data of the gravimetrical mixing of highly enriched 233U and 236U materials. It was verified by thermal ionization mass spectrometry (TIMS) measurements using the classical total evaporation (TE) and modified total evaporation (MTE) methods. The n( 234U)/ n( 236U), n( 235U)/ n( 236U) and n( 238U)/ n( 236U) ratios were then determined by TIMS using the n( 233U)/ n( 236U) ratio for internal normalization and using a multi-dynamic measurement procedure in order to circumvent any possible influence and uncertainties from Faraday cup efficiencies and amplifier gain factors. The certified n( 235U)/ n( 236U) and n( 238U)/ n( 236U) ratios were additionally verified using the classical and modified total evaporation methods using two TIMS instruments at IRMM and one TIMS instrument at IAEA-SGAS. The verification data can be regarded as results obtained at three independent instruments at two different nuclear safeguards laboratories.

A new method for isotope ratio measurement of uranium in trace amount by thermal ionization mass spectrometry: The continuous heating method

A new method for isotope ratio measurement with thermal ionization mass spectrometry (TIMS), “continuous heating method”, was developed in order to determine an accurate isotope ratio of uranium ranging from sub-picograms to several dozen picograms. In this method, signals were measured during evaporation of an entire sample in the same way as in the “total evaporation method”; however, part of the higher detected signals was used for calculation of the isotope ratio. The continuous heating method can measure the ratios with high reproducibility regardless of the sample amount and the skill of operators because procedures of measurement and data calculation were standardized, enabling accurate correction of the mass discrimination effect. By using the optimized procedures, the relative standard deviation (2 σ) of 235U/ 238U ratio in CRM U350 particle (35% 235U enrichment) with a diameter of about 1 μm was less than 2%. When 235U/ 238U ratios in IRMM 184 (natural uranium) solution samples of uranium of 0.4, 4 and 44 pg measured by the continuous heating method were compared with those measured by the conventional method and the total evaporation method, which were well-known methods of TIMS, there was no difference in the case of measurement of a larger amount of samples. However, the continuous heating method showed the most accurate result for the smallest amount of samples.

Application of the total evaporation technique to chromium isotope ratio measurement by thermal ionization mass spectrometry

The total evaporation technique of thermal ionization mass spectrometry was applied to the isotopic analysis of chromium. High measurement reproducibility of the chromium isotope ratios was verified (2 S.E. < 0.05% ( 53Cr/ 52Cr)), while a clear mass fractionation effect was observed by using conventional measurement technique. The chromium isotope ratios analyzed by the total evaporation method were not affected by the sample amount on the rhenium filament (50–500 ng Cr). The isotopic analysis under the coexistence of zinc was also performed, and its effect to the chromium isotope ratios was confirmed.