Determination of CMPO using HPLC -UV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gracy Elias; Gary S. Groenewold; Bruce J. Mincher

Octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) is an extractant proposed for selective separation of radionuclide metals from used nuclear fuel solutions using solvent extraction. Radiolysis reactions can degrade CMPO and reduce separation performance and hence methods for measuring concentration of CMPO and identifying degradation products are needed. A novel high performance liquid chromatography (HPLC) method employing ultraviolet detection (UV) was developed to detect and quantitate CMPO in dodecane. Some radiolysis products in gamma and alpha irradiated CMPO solutions were identified using HPLC/electrospray ionization-mass spectrometry (ESI-MS). Validation data indicated that the HPLC-UV method for CMPO determination provided good linearity, sensitivity, procedure accuracy and systemmore » precision. CMPO-nitric acid complexes were also identified, that account for the apparent loss of CMPO in acidic environment, independent of irradiation.« less

CMPO purity tests in the TRUEX solvent using americium-241

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brewer, K.N.; Herbst, R.S.; Tranter, T.J.

1993-12-01

The Transuranic Extraction (TRUEX) Process was developed by E.P. Horwitz and coworkers at Argonne National Laboratory (ANL) to separate the +4, +6, and +3 actinides from acidic aqueous solutions of nuclear wastes. Octyl (phenyl)-N-N-diisobutyl-carbamoylmethylphosphine oxide (CMPO) is the active actinide complexant used in the TRUEX solvent. CMPO is combined with tributyl phosphate (TBP) in an organic diluent, typically n-dodecane, to form the TRUEX solvent. Small quantities of impurities in the CMPO resulting from: (1) synthesis, (2) acid hydrolysis, or (3) radiolysis can result in actinide stripping problems from the solvent. The impurity, octylphenylphosphinic acid (POPPA), ia a powerful extractant atmore » low acid concentrations which may be formed during CMPO synthesis. Consequently, commercial CMPO may contain sufficient quantities of POPPA to significantly impact the stripping of actinides from the TRUEX solvent. The purpose of these tests was to (1) determine if commercially available CMPO is sufficiently pure to alleviate actinide stripping problems from the TRUEX process and (2) to determine if solvent cleanup methods are sufficient to purify the commercially purchased CMPO. Extraction and solvent cleanup methodologies used by Horwitz and coworkers at ANL were used to determine CMPO purity with {sup 241}Am. The improvement of the americium distribution coefficient in dilute nitric acid resulting from further purifying this CMPO is not significant enough to warrant additional CMPO purifying steps. The commercially purchased CMPO is found to be acceptable to use, as received, in a full-scale TRUEX process.« less

Lipophilic ternary complexes in liquid-liquid extraction of trivalent lanthanides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumetta, Gregg J.; Levitskaia, Tatiana G.; Latesky, Stanley

2012-03-01

The formation of ternary complexes between lanthanide ions [Nd(III) or Eu(III)], octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide (CMPO), and bis-(2-ethylhexyl)phosphoric acid (HDEHP) was probed by liquid-liquid extraction and spectroscopic techniques. Equilibrium modeling of data for the extraction of Nd(III) or Eu(III) from lactic acid media into n-dodecane solutions of CMPO and HDEHP indicates the predominant extracted species are of the type [Ln(AHA){sub 2}(A)] and [Ln(CMPO)(AHA){sub 2}(A)], where Ln = Nd or Eu and A represents the DEHP{sup -} anion. FTIR (for both Eu and Nd) and visible spectrophotometry (in the case of Nd) indicate the formation of the [Ln(CMPO)(A){sup 3}] complexes when CMPO ismore » added to n-dodecane solutions of the LnA{sub 3} compounds. Both techniques indicate a stronger propensity of CMPO to complex Nd(III) versus Eu(III).« less

Characterization of CMPO and its radiolysis products by Direct Infusion ESI-MS

DOE Office of Scientific and Technical Information (OSTI.GOV)

G. S. Groenewold; G. Elias; B. J. Mincher

2012-09-01

Direct infusion electrospray ionization-mass spectrometry (ESI-MS) approaches were developed for rapid identification of octyl,phenyl,(N,N-(diisobutyl)carbamoylmethyl) phosphine oxide (CMPO) and impurity compounds formed during alpha and gamma irradiation experiments. CMPO is an aggressive Lewis base, and produces extremely abundant metal complex ions in the ESI-MS analysis that make identification of low abundance compounds that are less nucleophilic challenging. Radiolysis products were identified using several approaches including restricting ion trapping so as to exclude the abundant natiated CMPO ions, extraction of acidic products using aqueous NaOH, and extraction of basic products using HNO3. These approaches generated protonated, natiated and deprotonated species derived frommore » CMPO degradation products formed via radiolytic cleavages of several different bonds. Cleavages of the amide and methylene-phosphoryl bonds appear to be favored by both forms of irradiation, while alpha irradiation also appears to induce cleavage of the methylene-carbonyl bond. The degradation products observed are formed from recombination of the initially formed radicals with hydrogen, methyl, isopropyl and hydroxyl radicals that are derived either from CMPO, or the dodecane solvent.« less

Radical Cations and Acid Protection during Radiolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mincher, Bruce J.; Zarzana, Christopher A.; Mezyk, Stephen P.

2016-09-09

Ligand molecules for used nuclear fuel separation schemes are exposed to high radiation fields and high concentrations of acid. Thus, an understanding of the complex interactions between extraction ligands, diluent, and acid is critical to understanding the performance of a separation process. The diglycolamides are ligands with important structural similarities to CMPO; however, previous work has shown that their radiolytic degradation has important mechanistic differences from CMPO. The DGAs do not enjoy radioprotection by HNO3 and the kinetics of DGA radiolytic degradation are different. CMPO degrades with pseudo-zero-order kinetics in linear fashion with absorbed dose while the DGAs degrade inmore » pseudo-first-order, exponential fashion. This suggests that the DGAs degrade by simple reaction with some product of direct diluent radiolysis, while CMPO degradation is probably multi-step, with a slow step that is not dependent on the CMPO concentration, and mitigated by HNO 3. It is thus believed that radio-protection and the zero-order radiolytic degradation kinetics are related, and that these phenomena are a function of either the formation of strong acid complexes with CMPO and/or to the presence of the CMPO phenyl ring. Experiments to test both these hypotheses have been designed and partially conducted. This report summarizes findings related to these phenomena for FY16, in satisfaction of milestone M3FT-16IN030104053. It also reports continued kinetic measurements for the reactions of the dodecane radical cation with solvent extraction ligands.« less

The radiolysis of CMPO: effects of acid, metal complexation and alpha vs. gamma radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruce J. Mincher; Stephen P. Mezyk; Gary S. Groenewold

Abstract The group actinide/lanthanide complexing agent octylphenylcarbamoylmethyl phosphine oxide (CMPO) has been examined for its radiation stability by measuring the kinetics of its reactions with free radicals in both the aqueous and organic phases for the free and metal-complexed ligand, identifying its degradation products for both alpha and gamma irradiation, measuring the effects on solvent extraction performance, and measuring the G-values for its degradation under various conditions. This includes the G-values for CMPO in the absence of, and in contact with the acidic aqueous phase, where it is shown that the acidic aqueous phase provides radio-protection for this ligand. Itmore » was found that both solvent and metal complexation affect the kinetics of the reaction of the •NO3 radical, a product of HNO3 radiolysis, with CMPO. For example, CMPO complexed with lanthanides has a rate constant for this reaction an order of magnitude higher than for the free ligand, and the reaction for the free ligand in the organic phase is about three times faster than in the aqueous phase. In steady state radiolysis kinetics it was determined that HNO3, although not NO3- anion, provides radio-protection to CMPO, with the G-value for its degradation decreasing with increasing acidity, until it was almost completely suppressed by irradiation in contact with 5 M HNO3. The same degradation products were produced by irradiation with alpha and gamma-sources, except that the relative abundances of these products varied. For example, the product of C-C bond scission was produced only in low amounts for gamma-radiolysis, but it was an important product for samples irradiated with a He ion beam. These results are compared to the new data appearing in the literature on DGA radiolysis, since CMPO and the DGAs both contain the amide functional group.« less

The TRUSPEAK Concept: Combining CMPO and HDEHP for Separating Trivalent Lanthanides from the Transuranic Elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumetta, Gregg J.; Gelis, Artem V.; Braley, Jenifer C.

2013-04-08

Combining octyl(phenyl)-N,N-diisobutyl-carbamoylmethyl-phosphine oxide (CMPO) and bis-(2-ethylhexyl) phosphoric acid (HDEHP) into a single process solvent for separating transuranic elements from liquid high-level waste is explored. Co-extraction of americium and the lanthanide elements from nitric acid solution is possible with a solvent mixture consisting of 0.1-M CMPO plus 1-M HDEHP in n-dodecane. Switching the aqueous-phase chemistry to a citrate-buffered solution of diethylene triamine pentaacetic acid (DTPA) allows for selective stripping of americium, separating it from the lanthanide elements. Potential strategies for managing molybdenum and zirconium (both of which co-extract with americium and the lanthanides) have been developed. The work presented here demonstratesmore » the feasibility of combining CMPO and HDEHP into a single extraction solvent for recovering americium from high-level waste and its separation from the lanthanides.« less

Combining CMPO and HEH[EHP] for Separating Trivalent Lanthanides from the Transuranic Elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braley, Jenifer C.; Lumetta, Gregg J.; Carter, Jennifer C.

2013-09-05

Combining octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide (CMPO) and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) into a single process solvent for separating transuranic elements from liquid high-level waste is explored. The lanthanides and americium can be co-extracted from HNO3 into 0.2 mol/L CMPO + 1.0 mol/L HEH[EHP] in n-dodecane. The extraction is relatively insensitive to the HNO3 concentration within 0.1 to 5 mol/L HNO3. Americium can be selectively stripped from the CMPO/HEH[EHP] solvent into a citrate-buffered N-(2-hydroxyethyl)ethylenediaminetriacetic acid solution . Separation factors >14 can be achieved in the range pH 2.5 to 3.7, and the separation factors are relatively insensitive to pH, a major advantagemore » of this solvent formulation.« less

Thermodynamic Insight into the Solvation and Complexation Behavior of U(VI) in Ionic Liquid: Binding of CMPO with U(VI) Studied by Optical Spectroscopy and Calorimetry.

PubMed

Wu, Qi; Sun, Taoxiang; Meng, Xianghai; Chen, Jing; Xu, Chao

2017-03-06

The complexation of U(VI) with octylphenyl-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO, denoted as L) in ionic liquid (IL) C 4 mimNTf 2 was investigated by UV-vis absorption spectrophotometry and isothermal titration calorimetry. Spectro-photometric titration suggests that three successive complexes, UO 2 L j 2+ (j = 1-3), formed both in "dry" (water content < 250 ppm) and "wet" (water content ≈ 12 500 ppm) ionic liquid. However, the thermodynamic parameters are distinctly different in the two ILs. In dry IL, the complexation strength between CMPO and U(VI) is much stronger, with stability constants of the respective complexes more than 1 order of magnitude higher than that in wet IL. Energetically, the complexation of U(VI) with CMPO in dry IL is mainly driven by negative enthalpies. In contrast, the complexation in wet IL is overwhelmingly driven by highly positive entropies as a result of the release of a large amount of water molecules from the solvation sphere of U(VI). Moreover, comparisons between the fitted absorption spectra of complexes in wet IL and that of extractive samples from solvent extraction have identified the speciation involved in the extraction of U(VI) by CMPO in ionic liquid. The results from this study not only offer a thermodynamic insight into the complexation behavior of U(VI) with CMPO in IL but also provide valuable information for understanding the extraction behavior in the corresponding solvent extraction system.

Separation of lanthanides and actinides using magnetic silica particles bearing covalently attached tetra-CMPO-calix[4]arenes.

PubMed

Böhmer, Volker; Dozol, Jean-François; Grüttner, Cordula; Liger, Karine; Matthews, Susan E; Rudershausen, Sandra; Saadioui, Mohamed; Wang, Pingshan

2004-08-21

Calix[4]arene tetraethers in the cone conformation bearing four -NH-CO-CH2-P(O)Ph2 (= CMPO) residues on their wide rim and one, two or four omega-amino alkyl residues of various lengths at the narrow rim were synthesized. Reaction with dichlorotriazinyl (DCT) functionalized magnetic particles led to complete coverage of the available surface by covalently linked CMPO-calix[4]arenes in all cases. Magnetically assisted removal of Eu(iii) and Am(iii) from acidic solutions was distinctly more efficient with these particles in comparison to analogous particles bearing the same amount of analogous single-chain CMPO-functions. The best result, an increase of the extraction efficiency by a factor of 140-160, was obtained for attachment via two propyl spacers. The selectivity Am/Eu was in the range of 1.9-2.8. No decrease of the extraction ability was observed, when the particles were repeatedly used, after simple back extraction with water.

Teacher Observation: Evaluation Report and Executive Summary

ERIC Educational Resources Information Center

Worth, Jack; Sizmur, Juliet; Walker, Matthew; Bradshaw, Sally; Styles, Ben

2017-01-01

The Teacher Observation intervention aimed to improve teacher effectiveness through structured peer observation. Teachers observe and are observed by their peers a number of times over the course of two years. It was delivered by the Centre for Market and Public Organisation (CMPO) at the University of Bristol. CMPO researchers trained lead…

The role of organic solvent radical cations in separations ligand degradation

DOE PAGES

Mezyk, Stephen P.; Mincher, Bruce J.; Dhiman, Surajdevprakash B.; ...

2015-11-04

The dodecane radical cation reaction rate constant with CMPO was measured using ps electron pulse radiolysis/absorption spectroscopy as k = (1.30 ± 0.11) x 1010 M -1 s -1 in dodecane/0.10 M CH 2Cl 2 solution. No reactivity increase occurred when these solutions were pre-contacted with nitric acid, similar to the behavior observed for TODGA. To corroborate these kinetic data with steady-state radiolysis measurements, where acid pre contacted CMPO showed significantly less degradation, it is proposed that the dodecane radical cation always reacts directly with TODGA, but for CMPO the charge-transfer occurs with the CMPO•HNO 3 complex formed in themore » acid contacted solvent.« less

Ship-in-a-bottle CMPO in MIL-101(Cr) for selective uranium recovery from aqueous streams through adsorption.

PubMed

De Decker, Jeroen; Folens, Karel; De Clercq, Jeriffa; Meledina, Maria; Van Tendeloo, Gustaaf; Du Laing, Gijs; Van Der Voort, Pascal

2017-08-05

Mesoporous MIL-101(Cr) is used as host for a ship-in-a-bottle type adsorbent for selective U(VI) recovery from aqueous environments. The acid-resistant cage-type MOF is built in-situ around N,N-Diisobutyl-2-(octylphenylphosphoryl)acetamide (CMPO), a sterically demanding ligand with high U(VI) affinity. This one-step procedure yields an adsorbent which is an ideal compromise between homogeneous and heterogeneous systems, where the ligand can act freely within the pores of MIL-101, without leaching, while the adsorbent is easy separable and reusable. The adsorbent was characterized by XRD, FTIR spectroscopy, nitrogen adsorption, XRF, ADF-STEM and EDX, to confirm and quantify the successful encapsulation of the CMPO in MIL-101, and the preservation of the host. Adsorption experiments with a central focus on U(VI) recovery were performed. Very high selectivity for U(VI) was observed, while competitive metal adsorption (rare earths, transition metals...) was almost negligible. The adsorption capacity was calculated at 5.32mg U/g (pH 3) and 27.99mg U/g (pH 4), by fitting equilibrium data to the Langmuir model. Adsorption kinetics correlated to the pseudo-second-order model, where more than 95% of maximum uptake is achieved within 375min. The adsorbed U(VI) is easily recovered by desorption in 0.1M HNO 3 . Three adsorption/desorption cycles were performed. Copyright © 2017 Elsevier B.V. All rights reserved.

Removal of radioactive and other hazardous material from fluid waste

DOEpatents

Tranter, Troy J [Idaho Falls, ID; Knecht, Dieter A [Idaho Falls, ID; Todd, Terry A [Aberdeen, ID; Burchfield, Larry A [W. Richland, WA; Anshits, Alexander G [Krasnoyarsk, RU; Vereshchagina, Tatiana [Krasnoyarsk, RU; Tretyakov, Alexander A [Zheleznogorsk, RU; Aloy, Albert S [St. Petersburg, RU; Sapozhnikova, Natalia V [St. Petersburg, RU

2006-10-03

Hollow glass microspheres obtained from fly ash (cenospheres) are impregnated with extractants/ion-exchangers and used to remove hazardous material from fluid waste. In a preferred embodiment the microsphere material is loaded with ammonium molybdophosphonate (AMP) and used to remove radioactive ions, such as cesium-137, from acidic liquid wastes. In another preferred embodiment, the microsphere material is loaded with octyl(phenyl)-N-N-diisobutyl-carbamoylmethylphosphine oxide (CMPO) and used to remove americium and plutonium from acidic liquid wastes.

A Selection of Test Cases for the Validation of Large-Eddy Simulations of Turbulent Flows (Quelques cas d’essai pour la validation de la simulation des gros tourbillons dans les ecoulements turbulents)

DTIC Science & Technology

1998-04-01

they approach the more useful (higher) Reynolds numbers. 8.6 SUMMARY OF COMPLEX FLOWS SQUARE DUCT CMPO00 UDOv 6.5 x 10’i E Yokosawa ei al. 164] pg...Sheets for: Chapter 8. Complex Flows 184 185 CMPOO: Flow in a square duct - Experiments Yokosawa , Fujita, Hirota, & Iwata 1. Description of the flow...These are the experiments of Yokosawa ei al (1989). Air was blown through a flow meter and a settling chamber into a square duct. Measuremsents were

Equilibrium of molybdenum in selected extraction systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tkac, Peter; Paulenova, Alena

2007-07-01

The concentration of molybdenum(VI) in dissolved irradiated nuclear fuel is comparable with the concentrations of Tc, Am and Np. Therefore it is of big interest to understand its behavior under conditions related to the UREX/TRUEX process. The effect of the poly-speciation of molybdenum in aqueous solution on its extraction by neutral solvents TBP and CMPO/TBP was studied. Extraction yields of molybdenum decreased significantly when AHA was added to aqueous phase. Our investigation confirmed a strong ability of the aceto-hydroxamic acid to form complexes with Mo in high acidic solutions. Spectroscopic data (UV-Vis) confirmed that a fraction of the Mo(VI)-AHA complexmore » is present in the organic phase after extraction. (authors)« less

Separation and preconcentration of actinides from concentrated nitric acid by extraction chromatography in microsystems.

PubMed

Losno, Marion; Pellé, Julien; Marie, Mylène; Ferrante, Ivan; Brennetot, René; Descroix, Stéphanie; Mariet, Clarisse

2018-08-01

An original method of monolith impregnation in microsystem for the analysis of radionuclides in nitric acid is reported. Three microcolumns made of monolith poly(AMA-co-EDMA) were impregnated in COC microsystems. The robustness of the microsystems in nitric acid media until 8 M was demonstrated. High exchange capacity and affinity for tetravalent and hexavalent actinides in concentrated nitric media were obtained. The retention characteristics of the microcolumns impregnated by TBP, TBP-CMPO and DAAP were compared with those of the equivalent commercial particulate resins TBP™, TRU™ and UTEVA™ respectively. The separation of U, Th and Eu was validated in a classical microsystem and a procedure is proposed in a centrifugal microsystem. Copyright © 2018. Published by Elsevier B.V.

Electrochemical assessment of water|ionic liquid biphasic systems towards cesium extraction from nuclear waste.

PubMed

Stockmann, T Jane; Zhang, Jing; Montgomery, Anne-Marie; Ding, Zhifeng

2014-04-22

A room temperature ionic liquid (IL) composed of a quaternary alkylphosphonium (trihexyltetradecylphosphonium, P66614(+)) and tetrakis(pentafluorophenyl)borate anion (TB(-)) was employed within a water|P66614TB (w|P66614TB or w|IL) biphasic system to evaluate cesium ion extraction in comparison to that with a traditional water|organic solvent (w|o) combination. (137)Cs is a major contributor to the radioactivity of spent nuclear fuel as it leaves the reactor, and its extraction efficiency is therefore of considerable importance. The extraction was facilitated by the ligand octyl(phenyl)-N,N'-diisobutylcarbamoylphosphine oxide (CMPO) used in TRans-Uranium EXtraction processes and investigated through well established liquid|liquid electrochemistry. This study gave access to the metal ion to ligand (1:n) stoichiometry and overall complexation constant, β, of the interfacial complexation reaction which were determined to be 1:3 and 1.6×10(11) at the w|P66614TB interface while the study at w|o elicited an n equal to 1 with β equal to 86.5. Through a straightforward relationship, these complexation constant values were converted to distribution coefficients, δ(α), with the ligand concentrations studied for comparison to other studies present in the literature; the w|o and w|IL systems gave δ(α) of 2 and 8.2×10(7), respectively, indicating a higher overall extraction efficiency for the latter. For the w|o system, the metal ion-ligand stoichiometries were confirmed through isotopic distribution analysis of mass spectra obtained by the direct injection of an emulsified water-organic solvent mixture into an electron spray ionization mass spectrometer. Copyright © 2014 Elsevier B.V. All rights reserved.

Managing Zirconium Chemistry and Phase Compatibility in Combined Process Separations for Minor Actinide Partitioning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wall, Nathalie; Nash, Ken; Martin, Leigh

In response to the NEUP Program Supporting Fuel Cycle R&D Separations and Waste Forms call DEFOA- 0000799, this report describes the results of an R&D project focusing on streamlining separation processes for advanced fuel cycles. An example of such a process relevant to the U.S. DOE FCR&D program would be one combining the functions of the TRUEX process for partitioning of lanthanides and minor actinides from PUREX(UREX) raffinates with that of the TALSPEAK process for separating transplutonium actinides from fission product lanthanides. A fully-developed PUREX(UREX)/TRUEX/TALSPEAK suite would generate actinides as product(s) for reuse (or transmutation) and fission products as waste.more » As standalone, consecutive unit-operations, TRUEX and TALSPEAK employ different extractant solutions (solvating (CMPO, octyl(phenyl)-N,Ndiisobutylcarbamoylmethylphosphine oxide) vs. cation exchanging (HDEHP, di-2(ethyl)hexylphosphoric acid) extractants), and distinct aqueous phases (2-4 M HNO 3 vs. concentrated pH 3.5 carboxylic acid buffers containing actinide selective chelating agents). The separate processes may also operate with different phase transfer kinetic constraints. Experience teaches (and it has been demonstrated at the lab scale) that, with proper control, multiple process separation systems can operate successfully. However, it is also recognized that considerable economies of scale could be achieved if multiple operations could be merged into a single process based on a combined extractant solvent. The task of accountability of nuclear materials through the process(es) also becomes more robust with fewer steps, providing that the processes can be accurately modeled. Work is underway in the U.S. and Europe on developing several new options for combined processes (TRUSPEAK, ALSEP, SANEX, GANEX, ExAm are examples). There are unique challenges associated with the operation of such processes, some relating to organic phase chemistry, others arising from the variable composition of the aqueous medium. This project targets in particular two problematic issues in designing combined process systems: managing the chemistry of challenging aqueous species (like Zr 4+) and optimizing the composition and properties of combined extractant organic phases.« less

Improvements in Cd stable isotope analysis achieved through use of liquid-liquid extraction to remove organic residues from Cd separates obtained by extraction chromatography.

PubMed

Murphy, Katy; Rehkämper, Mark; Kreissig, Katharina; Coles, Barry; van de Flierdt, Tina

2016-01-23

Organic compounds released from resins that are commonly employed for trace element separations are known to have a detrimental impact on the quality of isotopic analyses by MC-ICP-MS. A recent study highlighted that such effects can be particularly problematic for Cd stable isotope measurements (M. Gault-Ringold and C. H. Stirling, J. Anal. At. Spectrom. , 2012, 27 , 449-459). In this case, the final stage of sample purification commonly applies extraction chromatography with Eichrom TRU resin, which employs particles coated with octylphenyl- N , N -di-isobutyl carbamoylphosphine oxide (CMPO) dissolved in tri- n -butyl phosphate (TBP). During chromatography, it appears that some of these compounds are eluted alongside Cd and cannot be removed by evaporation due to their high boiling points. When aliquots of the zero-ε reference material were processed through the purification procedure, refluxed in concentrated HNO 3 and analyzed at minimum dilution (in 1 ml 0.1 M HNO 3 ), they yielded Cd isotopic compositions (ε 114/110 Cd = 4.6 ± 3.4, 2SD, n = 4) that differed significantly from the expected value, despite the use of a double spike technique to correct for instrumental mass fractionation. This result was accompanied by a 35% reduction in instrumental sensitivity for Cd. With increasing dilution of the organic resin residue, both of these effects are reduced and they are insignificant when the eluted Cd is dissolved in ≥3 ml 0.1 M HNO 3 . Our results, furthermore, indicate that the isotopic artefacts are most likely related to anomalous mass bias behavior. Previous studies have shown that perchloric acid can be effective at avoiding such effects (Gault-Ringold and Stirling, 2012; K. C. Crocket, M. Lambelet, T. van de Flierdt, M. Rehkämper and L. F. Robinson, Chem. Geol. , 2014, 374-375 , 128-140), presumably by oxidizing the resin-derived organics, but there are numerous disadvantages to its use. Here we show that liquid-liquid extraction with n -heptane removes the organic compounds, dramatically improving quality of the Cd isotope data for samples that are analyzed at or close to minimum dilution factors. This technique is quick, simple and may be of use prior to analysis of other isotope systems where similar resins are employed.