Lithium Formate Research Articles

A zero-liquid discharge process to recover all critical metals from spent NCM111 cathode material of end-of-life lithium-ion batteries: statistically optimized leaching with formic acid and in-situ crystallization

A green chemistry process has been developed to recycle cathode material from end-of-life lithium ion batteries. NCM111 (LiNi1/3Co1/3Mn1/3O2) was completely leached with 13 M formic acid to produce two groups of salts with different solubilities: sparingly soluble cobalt, manganese, and nickel (CMN) formates and highly soluble lithium formate. During leaching, CMN formate salts exceeded their solubility limit in the pregnant leach solution (PLS) and crystallized. Mixed CMN formate salts were recovered by filtering the PLS. Lithium was completely recovered by evaporating the filtered PLS then thermally decomposing the lithium formate obtained in air to lithium carbonate. The purity of the lithium carbonate was 98.1 wt%.The leaching process was optimized through response surface methodology experiments. The minimum time required to completely leach NCM111 with 13 M formic acid was 30.8 h. Optimum leaching conditions were L/S = 2.81 mL/g (equivalent to S/L = 356 g/L) and T = 95 °C. During leaching, 98% of CMN formate salts exceeded their solubility limit and crystallized from the PLS.The recycling process is simple and generates no liquid or solid waste products. The only reagent is 13 M formic acid. The only by-products are water vapour, which can be condensed and reused, and carbon dioxide gas.

Selection and purification of Li2CO3 precursor for bolometric double beta decay experiments

This paper describes the preparation of radiopure lithium carbonate powder for the needs of low-background research, in particular, AMoRE-II, the second phase of a search for the neutrinoless double-beta decay (0νDBD) of the 100Mo isotope using over 100 kg of 100Mo contained in 200 kg of ultra-pure Li2100MoO4 bolometric crystals. About 150 kg of pure Li2CO3 powder is required to synthesize the crystals. The desired radiopurity for the lithium powder is 40K below 100 mBq/kg, and Th/U and Ra are at a few mBq/kg. Several commercially available powders were tested with ICP-MS and HPGe detectors at the Center for Underground Physics (CUP) of the Institute for Basic Science in Korea. The lowest purity of the tested products was 99.99%. The results of the powders’ radioassay at CUP showed that none of the tested products were suited for the 0νDBD search application. A special purification technology had to be developed to remove the original contamination of the powder with potassium (K), thorium (Th), uranium (U), and radium (Ra). Lithium carbonate crystallization via carbonization technique was inefficient in removing radiochemical impurities. Lithium formate fractional recrystallization effectively removed Ra, K, and Th, but the synthesis of the final lithium carbonate product had a low yield and required the introduction of additional chemicals. The analysis results of raw and purified powders, the decontamination efficiency, and plans are described in the article.

Thermodynamic Modeling of the Drowning-Out Crystallization Process for LiOH and CHLiO2

This study focuses on the thermodynamic modeling of the crystallization by the drowning process for two lithium salts: lithium hydroxide (LiOH) and lithium formate (CHLiO2). The modeling involves utilizing thermodynamic properties, such as the activity, osmotic, and solubility coefficients, within the ternary systems of LiOH + cosolvent + water and CHLiO2 + cosolvent + water, as well as their respective binary constituent systems. Ethanol is chosen as the cosolvent for both salts, facilitating a comparative analysis. Given the limited availability of thermodynamic data for lithium formate with different cosolvents, the study aims to address this gap. The modified Pitzer model was employed for the modeling process, where the parameters were successfully obtained for both systems, with a deviation of less than 1%. Additionally, the mass and energy balance for the drowning-out crystallization process of both salts was performed.

Improvement of neutron sensitivity for lithium formate EPR dosemeters: a Monte Carlo analysis.

This work presents the computational analysis of the sensitivity improvements that could be achieved in lithium formate monohydrate (LFM) electron paramagnetic resonance (EPR) dosemeters exposed to neutron beams. Monte Carlo (MC) simulations were performed on LFM pellets exposed to neutron beams with different energy spectra at various depths inside a water phantom. Various computations were carried out by considering different enrichments of 6Li inside the LFM matrix as well as addition of different amounts of gadolinium oxide inside the pellet blend. The energy released per unit mass was calculated with the aim of predicting the increase in dose achievable by the addition of sensitizers inside the pellets. As expected, a larger amount of 6Li induces an increase of energy released because of the charged secondary particles (i.e. 3H ions and α-particles) produced after neutron capture. For small depths in water phantom and low-energy neutron spectra the dose increase due to 6Li enrichment is high (more than three orders of magnitude with respect to the case of with 7Li). In case of epithermal neutron beams the energy released in 6Li-enriched LFM compound is smaller but larger than in the case of fast neutron beams. On the other hand, the computational analysis evidenced that gadolinium is less effective than 6Li in improving neutron sensitivity of the LFM pellets. Discussion based on the features of MC transport code is provided. This result suggests that 6Li enrichment of LFM dosemeters would be more effective for neutron sensitivity improvement and these EPR dosemeters could be tested for dosimetric applications in Neutron Capture Therapy.

Cumulative dose experiments on Lithium formate monohydrate as an EPR-dosimeter for use in different radiation therapy scenarios

The Electron Paramagnetic Resonance (EPR) method can be employed to read out the absorbed dose of suitable materials exposed to ionizing radiation. In this work, we study the dosimetric properties of lithium formate monohydrate (LFM) irradiated by X-rays, electrons and protons in order to use it as dosimeter in radiotherapy, including hadrontherapy. The responses of the cumulative doses received by a single dosimeter were analyzed in order to investigate the feasibility and possibility of using a single dosimeter per patient for all therapy fractions. A perfect linearity of the LFM dosimetry curves is observed, with an acceptable degree of accuracy exceeding 99%. LFM seems to be slightly more sensitive to X-ray photons compared to proton and electron irradiations with a rate of about 16% and 10% respectively. The analysis of the effect of cumulative doses revealed acceptable accuracy and reliability of the results. Indeed, the dosimetry curves obtained with several dosimeters having received a single dose (reference curve) and those obtained with a single dosimeter having received several cumulative doses are completely superposable with relatively acceptable uncertainties, which is found to be less than 5%.

Diffusiophoretic Movements of Polystyrene Particles in a H-Shaped Channel for Inorganic Salts, Carboxylic Acids, and Organic Salts.

Diffusiophoresis is the movement of particles as a result of a concentration gradient, where the particles can move toward higher concentrations. The magnitude of the movement is largest for the electrolyte solute and depends upon the relative concentration gradient, surface potential, and diffusivity contrast between the cation and anion. Here, diffusiophoresis of ordinary polystyrene particles is studied in a H-shaped channel for different solutes. The experimental results are compared to a numerical model, which is solely based on the concentration gradient, surface potential, and diffusivity contrast. The surface potential of the particles was measured to use as input for the numerical model. The diffusiophoretic movement of the experiments aligns well with the theoretical predicted movement for the inorganic (lithium chloride and sodium bicarbonate) and organic (lithium formate, sodium formate, and potassium formate) salts measured. However, for the carboxylic acids (formic, acetic, and oxalic acids) measured, the theoretical model and experiment do not align because they are weak acids and only partially dissociate, creating a driving force for diffusiophoresis. Overall, the H-shaped channel can be used in the future as a platform to measure diffusiophoretic movement for more complex systems, for example, with mixtures and asymmetric valence electrolytes.

Lithium salts: assessment of their chronic and acute toxicities to honey bees and their anti-Varroa field efficacy.

Varroa control is essential for the maintenance of healthy honey bee colonies. Overuse of acaricides has led to the evolution of resistance to those substances. Studies of the short-term acaricidal effects and safety of various lithium (Li) salts recently have been reported. This study examined the long-term in vitro and in vivo bee toxicities, short-term motor toxicity to bees and long-term anti-Varroa field efficacy of several Li salts. In an in vitro chronic-toxicity assay, lithium citrate (18.8mm) was the most toxic of the examined salts, followed by lithium lactate (29.5mm), and lithium formate (32.5mm). In terms of acute locomotor toxicity to bees, all of the Li salts were well-tolerated and none of the treatment groups differed from the negative control group. In an in vitro survival study, all of the Li treatments significantly reduced bee life spans by a factor of 1.8-7.2, as compared to the control. In terms of life expectancy, lithium citrate was the most toxic salt, with no significant differences noted between lithium formate and lithium lactate. In the bee-mortality field study, none of the examined treatments differed from the negative control. Amitraz and lithium formate exhibited similar acaricide effects, which were significantly different from those observed for lithium lactate and the negative control. In light of lithium formate's honey bee safety and efficacy as an acaricide, additional sublethal toxicity studies in brood, drones and queens, as well as tests aimed at the optimization of administration frequency are warranted. © 2022 Society of Chemical Industry.

Radicals in ammonium tartrate at 295 K by X-radiation: Revised radical structures by EMR and DFT analyses

The simple amino acid l-α-alanine (ala) in polycrystalline form was among the first substances to be proposed and subsequently developed for Electron Paramagnetic Resonance (EPR)-based solid state radiation dosimetry. One disadvantage with ala is a relatively low sensitivity for doses below a few gray (Gy) which is a dose range of particular interest in medical, accident and environmental applications. A number of other compounds have been screened and some of these have shown a better sensitivity to radiation exposure than ala, in some cases up to a factor of 7–8. In particular ammonium tartrate (AT) and lithium formate (LiFo) have been taken into practical use. The present work was initially aimed to investigate the low-temperature radical products in AT, and the reactions leading to the product of dosimetric interest at room temperature. As a part of these studies, the previously characterized major room temperature radical product was re-investigated using single crystal electron magnetic resonance (EMR) techniques combined with periodic density functional theory (DFT) -type quantum chemical calculations. Surprisingly, this study showed that the molecular structure of the dominant radical at room temperature is somewhat different from that previously proposed. Furthermore, a second room temperature radical, previously not well characterized, was carefully investigated and three hyperfine coupling tensors were determined. These three tensors were sufficient to simulate all experimental observations for the second radical but not alone sufficient to permit an unambiguous molecular structure of the defect to be determined. It appears that the EPR resonance from this radical does not influence the dosimetric potential of AT.

LiAlO<sub>2</sub> prepared by nitrates-free synthesis for carbon capture by MCFCs

The pure crystalline phase of alpha lithium aluminate, the state-of-the-art matrix support material, was directly prepared by two nitrates-free methods at 650 °C. A solgel method included pyrolysis of a colloidal mixture of aluminum hydroxide sol and lithium formate. The advantages of the used formate pyrolysis are the absence of nitrogen oxide emission in comparison to other combustion methods as well as it provides high homogeneity of a product. The solid-state reaction is a conventional method used in industry so the optimal powder-to-ball weight ratio was found in this study to give a high surface area. Described methods of synthesis are easy, economic and low-emission methods for the preparation of submicron α-LiAlO<sub>2</sub> powders with the surface area of about 25‒27 m 2 /g which is optimal for application as matrix material in мolten сarbonate fuel cells.

Suitability of superficial electron paramagnetic resonance dosimetry for in vivo measurement and verification of cumulative total doses during IMRT: A proof of principle

PurposeThe present study investigates superficial in vivo dosimetry (IVD) by means of a previously proposed electron paramagnetic resonance (EPR) dosimetry system aiming at measuring and verifying total doses delivered by complex radiotherapy treatments. In view of novel regulatory requirements in Germany, differences between measured and planned total doses to the EPR dosimeters are analyzed and compared to reporting thresholds for significant occurrences. MethodsEPR dosimeters, each consisting of one lithium formate monohydrate (LFM) and one polycrystalline l-alanine (ALA) pellet, were attached to the surface of an anthropomorphic head phantom. Three head and neck treatments with total target doses ranging from 30 to 64Gy were fully delivered to the phantom by helical tomotherapy. During each treatment, eight EPR dosimeters were placed at distinct spots: (i) within or next to the planning target volume (PTV), (ii) near to organs at risk including the parotids and the lenses, (iii) at the thyroid lying out-of-field. EPR read out was always performed after all fractions were delivered. EPR results were compared to thermoluminescence dosimeter (TLD) measurements and to the planned total doses derived from the treatment planning system (TPS). Planned total doses to the EPR dosimeters ranged from about 2 to 64Gy. ResultsBy taking uncertainties into account, the measured and planned doses were in good agreement. Exceptions occurred mainly at the thyroid (out-of-field) and lenses (extreme sparing). The maximum total dose difference between EPR results and corresponding planned doses was 1.3Gy occurring at the lenses. Remarkably, each LFM and ALA pellet placed within or next to the PTV provided dose values that were within ±4% of the planned dose. Dose deviations from planned dose values were comparable for EPR and TLD measurements. ConclusionThe results of this proof of principle study suggests that superficial EPR-IVD is applicable in a wide dose range and in various irradiation conditions – being a valuable tool for monitoring cumulative total doses delivered by complex IMRT treatments. EPR-IVD in combination with helical tomotherapy is suitable to reliably detect local dose deviations at superficial dosimeter spots in the order of current national reporting thresholds for significant occurrences (i.e. 10%/4Gy).

Gellan gum gel tissue phantoms and gel dosimeters with tunable electrical, mechanical and dosimetric properties

Gellan gum gels have been proposed as tissue- and water-mimicking materials (phantoms) applied in medical imaging and radiotherapy dosimetry. Phantoms often require ionic additives to induce desirable electrical conductivity, resistance to biological spoilage, and radical scavenging properties. However, gellan gum is strongly crosslinked by the typically used sodium salts, forming difficult-to-work with gels with reduced optical clarity. Herein we investigated lithium and tetramethylammonium chloride to induce the required electrical conductivity while maintaining optical clarity; lithium formate and methylparaben were used as a radical scavenger and antimicrobial additive, respectively. Using a multifactorial design of experiments, we studied and modeled the electrical and mechanical properties and liquid expulsion (syneresis) properties of the gels. Finally, by the addition of a radiation-sensitive tetrazolium salt, dosimeters with favorable properties were produced. The results described herein may be used to prepare tissue phantoms and dosimeters with tuned electrical, mechanical, and dosimetric properties.

Determination of biogenic amines in tomato by ion-pair chromatography coupled to an amine-selective potentiometric detector

It is described the determination of underivatized biogenic amines by ion-pair chromatography coupled to potentiometric detection, for food quality control. A wall-jet flow-cell was used to hold an amine-selective electrode, based on cucurbit[6]uril as an ionophore, and a commercial reference electrode. The biogenic amines were separated in less than 20 min using a C18 column as the stationary phase. This method comprises a gradient elution with a mobile phase containing lithium formate buffer, acetonitrile, and butane-sulfonic acid sodium salt as an ion-pair agent. The proposed method was validated following the International Council for harmonization guidelines. Calibration data fitted a linear regression model with R2 varying from 0.9804 to 0.9972. Repeatability intra and inter-day showed relative standard deviation values lower than 9.1% and 13.3%, respectively. Detection and quantification limits ranged from 0.03 to 0.20 mg L−1 and 0.09 to 0.61 mg L−1, respectively. Spiked tomato samples were analysed to assess the accuracy, yielding recovery values from 85.8 to 108.5%. The biogenic amines content in fresh tomatoes, canned chopped tomato, and pulp tomato was 7.11, 5.12, and 7.69 mg L−1, respectively.

A practical EPR dosimetry system for routine use in radiotherapy: uncertainty analysis of lithium formate dosimeters at the therapeutic dose level

In electron paramagnetic resonance (EPR) dosimetry, solid dosimeter materials such as alanine (AL) or, more recently, lithium formate monohydrate (LFM) are typically used. These materials offer high potential for applications in radiotherapy based on their favorable dosimetric properties. Nevertheless, EPR dosimetry is not widespread in the clinics. This work presents an uncertainty analysis of EPR dosimetry in the dose range from 1 to 70 Gy using a compact spectrometer and applying a practical procedure being suitable for routine use in radiotherapy. The performances of self-pressed LFM pellets and commercial AL pellets are compared side by side.All pellets had a diameter of 4 mm and a height of 2 mm (AL) or 4 mm (LFM). The mean pellet mass was 35.81 mg and 73.81 mg for AL and LFM, respectively. Before irradiation, the pellets were stored for at least 8 weeks at 34 ± 2% relative humidity. For irradiation, the pellets were put inside an airtight capsule. In total, 25 pellets per material were examined. The pellets were irradiated at a temperature of 25 ± 2.5 (2σ) °C to doses of either 1, 5, 20, 50 or 70 Gy (five pellets per dose value and material) by a clinical 6 MV photon beam. Measurement uncertainties were obtained from five independent readouts per pellet within five weeks following irradiation using a benchtop EPR spectrometer. The measurement time of a single readout was restricted to 10 min per pellet. Dose values were derived from EPR signal amplitudes using a specifically developed spectral fitting procedure. Signal fading characteristics were analyzed and taken into account during evaluation.The relative dose uncertainties (1σ) for a single readout at doses ≥ 5 Gy are below 2.8% (AL) and 1.1% (LFM) but increase to 12.3% (AL) and 2.6% (LFM) at 1 Gy. By averaging five independent readouts, the uncertainties at 1 Gy decrease to 2.6% (AL) and 0.8% (LFM).In terms of dose uncertainty, the LFM pellets are superior to the commercial AL pellets owing to their narrower EPR spectrum and approximately doubled mass resulting in higher EPR signal intensities. In case of the LFM pellets, the EPR dosimetry system shows a high level of precision (< 3%) down to 1 Gy being preferable for applications in radiotherapy. The uncertainties can be further decreased by averaging multiple dose values from independent readouts.

Observation of Magic Number Clusters from Thermal Dissociation Molecular Dynamics Simulations of Lithium Formate Ionic Clusters.

Molecular dynamics (MD) simulations are well positioned to elucidate the aspects of electrospray ionization (ESI) and high-energy collision dissociation (HCD), as well as give insight into processes that involve neutral species that cannot be observed experimentally in ESI, HCD, and collision-induced dissociation (CID). Here, we utilize temperature dissociation molecular dynamics (TDMD) to model the HCD/CID of lithium formate clusters carrying a single positive charge. These simulations successfully reproduce the experimental ESI HCD spectra of lithium formate solutions and also support the existence of magic number clusters (MNCs) that have been observed. The simulations also provide strong evidence that the main fragmentation channel of such clusters involves neutral (LiHCOO)2 dimers.

A dual natural lithium formate/L-alanine EPR dosimeter for a mixed radiation field in a boron neutron capture therapy irradiation facility

Standard commercial L-alanine pellets and specially prepared natural lithium formate monohydrate powder samples of specific granulometry were irradiated in a 60Co gamma-ray irradiation plant and in the mixed field (thermal neutrons and gamma photons) of a boron neutron capture therapy (BNCT) experimental facility. The γ-doses applied with the 60Co source range from 0.1 to 50 kGy, while those in the BNCT facility go from ~7 Gy to 150 Gy. The thermal neutron fluences range from 1012 neutrons cm−2 to 2 1013 neutrons cm−2. The irradiation of materials promotes the creation of stable electronic defects (generally free radicals) which constitute paramagnetic centers that can be detected and quantified by electron paramagnetic resonance (EPR). After irradiation, the EPR characterization of the samples was performed by determining the EPR intensity of the spectrum relative to a reference standard constituted by Mn2+ impurities diluted into a MgO single crystal. As expected, L-alanine has revealed to be largely insensitive to thermal neutrons fluence in the investigated range. On the contrary, it is shown that the EPR intensity of irradiated natural lithium formate monohydrate powders is clearly sensitive to thermal neutrons and has a linear dependence with the γ-dose. We propose a dual dosimeter by combining L-alanine pellets and formate powders that would allow to determine the γ-dose and thermal neutron fluence in a selected position of the BNCT irradiation facility. Moreover, we demonstrate that the 6Li enrichment that has been proposed in the literature to enhance the performance of lithium-based EPR dosimeters is not crucial in our case. Instead, the natural isotopic abundance of lithium is large enough to obtain a satisfactory sensibility to thermal neutrons in our BNCT facility for fluencies >1012 neutrons cm−2.

Nickel-catalyzed carboxylation of aryl iodides with lithium formate through catalytic CO recycling.

A protocol for the Ni-catalyzed carboxylation of aryl iodides with formate has been developed with good functional group compatibility for the synthesis of a variety of aromatic carboxylic acids under mild conditions. The reaction tolerates other functionalities for cross-coupling, such as aryl bromide, aryl chloride, aryl tosylate, and aryl pinacol boronate. The reaction proceeds through a carbonylation process with in situ generated carbon monoxide in the presence of a catalytic amount of acetic anhydride and lithium formate, avoiding the use of gaseous CO. The strategy of CO recycling in catalytic amounts is critical for the success of the reaction.

Development of a CE-MS method for the study of riociguat and metabolite M1 in pharmaceutical analysis.

Riociguat is a novel antihypertensive drug for the treatment of pulmonary hypertension. We present electrophoretic characterization, i.e. migration behavior of riociguat and metabolite M1 as support for optimized CZE/MS assay. Fundamental separation parameters, such as peak width, symmetry, and resolution are studied in a series of ammonium formate buffers within pH range 2.60-5.61. The narrow region of peak symmetry lies close to pH 4.0 for both analytes. Accordingly, the value of resolution maximizes in a background electrolyte adjusted to pH 4.10. Basic calibration parameters estimated from CZE experiments with absorption photometric and mass spectrometric detection of riociguat and metabolite M1 were evaluated. More than three orders lower LOD was achieved with high resolution mass spectrometric detection. The observed difference in the sensitivity of both detection techniques gives priority to the utilization of CZE/MS in practice. The values of dissociation constants of riociguat and metabolite M1, pKBH , were determined from CZE measurements in lithium formate and lithium acetate background electrolytes with constant ionic strength. The value of pKBH = 4.30±0.02 for riociguat corresponds well to the value already presented in the literature. According to our observation, metabolite M1 behaves like a slightly stronger base with estimated pKBH = 4.40±0.02.

Verification of lithium formate monohydrate in 3D-printed container for electron paramagnetic resonance dosimetry in radiotherapy

The nondestructive dosimetry achieved with electron paramagnetic resonance (EPR) dosimetry facilitates repetitive recording by the same dosimeter to increase the reliability of data. In precedent studies, solid paraffin was needed as a binder material to make the lithium formate monohydrate (LFM) EPR dosimeter stable and nonfragile; however, its use complicates dosimetry. This study proposes a newly designed pure LFM EPR dosimeter created by inserting LFM into a 3D-printed container. Dosimetric characteristics of the LFM EPR dosimeter and container, such as reproducibility, linearity, energy dependence, and angular dependence, were evaluated and verified through a radiation therapy planning system (RTPS). The LFM EPR dosimeters were irradiated using a clinical linear accelerator. The EPR spectra of the dosimeters were acquired using a Bruker EMX EPR spectrometer. Through this study, it was confirmed that there is no tendency in the EPR response of the container based on irradiation dose or radiation energy. The results show that the LFM EPR dosimeters have a highly sensitive dose response with good linearity. The energy dependence across each photon and electron energy range seems to be negligible. Based on these results, LFM powder in a 3D-printed container is a suitable option for dosimetry of radiotherapy. Furthermore, the LFM EPR dosimeter has considerable potential for in vivo dosimetry and small-field dosimetry via additional experiments, owing to its small effective volume and highly sensitive dose response compared with a conventional dosimeter.

CHARACTERIZATION OF A LITHIUM FORMATE EPR-DOSIMETRY SYSTEM FOR PROTON RADIATION THERAPY.

The specific aim for the characterization of the lithium formate dosimetry system is to determine response and stability in a proton beam. The long-term goal for this investigation is an audit system for proton therapy like the end-to-end dose determinations performed for radiotherapy with photons. For a 150-MeV proton beam, the dose response was found to be linear in the dose interval 0-8.8 Gy. The accuracy of dose reconstruction was controlled in a blind test, in which the dose of 6.63 Gy was measured in samples irradiated with a real dose of 6.70 Gy. The stability was determined by irradiations of sets of four dosimeters every week during 1 month and analyzed at the same day thereafter. The fitting of the fading curve was done with a second-order polynomial resulting in a 6.6% lower value compared to the reference after 31 d.

Analysis by EPR measurements and spectral deconvolution of the dosimetric properties of lithium formate monohydrate

Abstract In this study we analyze the Electron Paramagnetic Resonance “EPR” response of lithium formate monohydrate “LFM” irradiated by photons and electrons using a linear accelerator. EPR measurements were performed one day after irradiation and regularly during six months of storage. Both dosimetric curves using peak to peak technique and double integration method showed linear behavior. The time dependence indicates good stability of free radicals produced on this material. The determined measurable threshold dose is 0.55 Gy. For used energies, LFM dosimeters are more sensitive to X-ray irradiation than to electrons. The deconvolution of the EPR signal of irradiated LFM using Levenberg-Marquardt (M-L) algorithm shows that this spectrum is constituting of three gaussian contributions. Each contribution has a linear evolution according to the irradiation dose, as well as an acceptable degree of stability during the storage period, approving the stability of all free radicals produced in LFM. All these characteristics confirm that LFM might be a promising dosimeter to be used in the ‘clinical’ dose range in radiotherapy.