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1.
A one-pot-two-step labeling of an oligonucleotide with an 18F-ArBF 3?(aryltrifluoroborate) radioprosthetic is reported herein. In order to characterize labeling in terms of radiochemistry, phosphorus-32 was also introduced to the 5′-terminus of the oligonucleotide via enzymatic phosphorylation. A pendant azide group was subsequently conjugated to the 5′-phosphate of the oligonucleotide. Copper(I) catalyzed [2+3] cycloaddition was undertaken to conjugate an alkyne-bearing 18F-ArBF 3? to the oligonucleotide. Following polyacrylamide gel electrophoresis, this doubly-labeled bioconjugate exhibited decay properties of both the phosphorus-32 and fluorine-18, that were confirmed by autoradiography at selected lengths of time, which in turn provided concrete evidence of successful conjugation. These results are corroborated by HPLC analysis of the labeled material. Taken together this work demonstrates viable use of 18F-ArBF 3? prosthetics for labeling oligonucleotides for use in PET imaging. 相似文献
2.
δ 18O P values and 87Sr/ 86Sr ratios were determined on disarticulated xenacanthiform, hybodontid and ctenacanthid shark tooth material from several Early Permian (Sakmarian–Kungurian) continental bone beds of northern Texas and southern Oklahoma as well as from the marine Middle Permian (Roadian) of northern Arizona. The δ 18O P values derived from the teeth of bone beds are in the range of 17.6–23.5‰ VSMOW, and are mostly depleted in 18O by 0.5–5‰ relative to proposed coeval marine δ 18O P values. This indicates an adaptation to freshwater habitats on the Early Permian coastal plain by several sharks. Distinctly higher δ 18O P values from two bone beds are attributed to significant evaporative enrichment in 18O in flood plain ponds. 87Sr/ 86Sr ratios of around 0.71077 are notably more radiogenic than 87Sr/ 86Sr of contemporaneous seawater. In contrast, the isotopic composition of teeth from the marine Kaibab Formation is characterised by low δ 18O P values in the range of 13.4–15.6‰ VSMOW while 87Sr/ 86Sr ratios of around 0.70821 are closer to the Roadian seawater value. The distinctly depleted δ 18O P values cannot be readily explained by fluvially affected freshening in a nearshore marine environment, so a diagenetic alteration of the Kaibab material seems to be more likely, excluding it from further interpretation. 相似文献
3.
Phosphorus (P) nutrition of beech ecosystems depends on soil processes, plant internal P cycling and P acquisition. P uptake of trees in the field is currently not validated due to the lack of an experimental approach applicable in natural forests. Application of radiolabelled tracers such as 33P and 32P is limited to special research sites and not allowed in natural environments. Moreover, only one stable isotope of P, namely 31P, exists. One alternative tool to measure P acquisition in the field could be the use of 18O‐labelled 31P‐phosphate ( 31P 18O 4 3?). Phosphate (P i) uptake rates calculated from the 18O enrichment of dried root material after application of 31P i 18O 4 3? via nutrient solution was always lower compared to 33P incorporation, did not show increasing rates of P i uptake at P deficiency under controlled conditions, and did not reveal seasonal fluctuations in the field. Consequently, a clear correlation between 33P‐based and 18O‐based P i uptake by roots could not be established. Comparison of P i uptake rates achieved from 33P‐P i and 18O‐P i application led to the conclusion of high P i metabolism in roots after P i uptake. The replacement of 18O by 16O from water in 18O‐P i during root influx, but most probably after P i uptake into roots, due to metabolic activities, indicates high and fast turnover of P i. Hence, the use of 18O‐P i as an alternative tool to estimate P i acquisition of trees in the field must consider the increase of 18O abundance in root water that was disregarded in dried root material. 相似文献
4.
Here we report bone phosphate oxygen (δ 18O p) values from perinates/neonates and infants (<3.5 years; n = 32); children (4–12 years; n = 12); unsexed juveniles (16–18 years; n = 2); and adult bones ( n = 17) from Wharram Percy, North Yorkshire, England, in order to explore the potential of this method to investigate patterns of past breastfeeding and weaning. In prior studies, δ 15N and δ 13C analyses of bone collagen have been utilized to explore weaning age in this large and well‐studied assemblage, rendering this material highly appropriate for the testing and development of this alternative method targeting the inorganic phase of bone. Data produced reveal 18O‐enrichment in the youngest perinatal/neonatal and infant samples, and an association between age and bone δ 18O p (and previously‐published δ 15N values), with high values in both these isotope systems likely due to breastfeeding. After the age of 2–3 years, δ 18O p values are lower, and all children between the ages of 4 and 12, along with the vast majority of sub‐adults and adults sampled (aged 16 to >50 years), have δ 18O p values consistent with the consumption of local modern drinking water. The implications of this study for the reconstruction of weaning practices in archaeological populations are discussed, including variations observed with bone δ 15N coll and δ 18O p co‐analysis and the influence of culturally‐modified drinking water and seasonality. The use of this method to explore human mobility and palaeoclimatic conditions are also discussed with reference to the data presented. Am J Phys Anthropol 157:226–241, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
5.
The 18O signature of atmospheric water vapour (δ 18O V) is known to be transferred via leaf water to assimilates. It remains, however, unclear how the 18O-signal transfer differs among plant species and growth forms. We performed a 9-hr greenhouse fog experiment (relative humidity ≥ 98%) with 18O-depleted water vapour (−106.7‰) on 140 plant species of eight different growth forms during daytime. We quantified the 18O-signal transfer by calculating the mean residence time of O in leaf water (MRT LW) and sugars (MRT Sugars) and related it to leaf traits and physiological drivers. MRT LW increased with leaf succulence and thickness, varying between 1.4 and 10.8 hr. MRT Sugars was shorter in C 3 and C 4 plants than in crassulacean acid metabolism (CAM) plants and highly variable among species and growth forms; MRT Sugars was shortest for grasses and aquatic plants, intermediate for broadleaf trees, shrubs, and herbs, and longest for conifers, epiphytes, and succulents. Sucrose was more sensitive to δ 18O V variations than other assimilates. Our comprehensive study shows that plant species and growth forms vary strongly in their sensitivity to δ 18O V variations, which is important for the interpretation of δ 18O values in plant organic material and compounds and thus for the reconstruction of climatic conditions and plant functional responses. 相似文献
6.
Traditional bulk stable isotope (δ 18O and δ 13C) and clumped isotope (Δ 47) records from bivalve shells provide invaluable histories of Earth's local and global climate change. However, biologically driven isotopic fractionations (BioDIFs) can overprint primary environmental signals in the shell. Here, we explore how conventional measurements of δ 18O, δ 13C, and Δ 47 in bivalve shells can be re-interpreted to investigate these physiological processes deliberately. Using intrashell Δ 47 and δ 18O alignment as a proxy for equilibrium state, we separately examine fractionations and/or disequilibrium occurring in the two major stages of the biomineralisation process: the secretion of the extrapallial fluid (EPF) and the precipitation of shell material from the EPF. We measured δ 18O, δ 13C, and Δ 47 in fossil shells representing five genera ( Lahillia, Dozyia, Eselaevitrigonia, Nordenskjoldia, and Cucullaea) from the Maastrichtian age [66–69 million years ago (Ma)] López de Bertodano Formation on Seymour Island, Antarctica. Material was sampled from both the outer and inner shell layers (OSL and ISL, respectively), which precipitate from separate EPF reservoirs. We find consistent δ 18O values across the five taxa, indicating that the composition of the OSL can be a reliable palaeoclimate proxy. However, relative to the OSL baseline, ISLs of all taxa show BioDIFs in one or more isotopic parameters. We discuss/hypothesise potential origins of these BioDIFs by synthesising isotope systematics with the physiological processes underlying shell biomineralisation. We propose a generalised analytical and interpretive framework that maximises the amount of palaeoenvironmental and palaeobiological information that can be derived from the isotopic composition of fossil shell material, even in the presence of previously confounding ‘vital effects’. Applying this framework in deep time can expand the utility of δ 18O, δ 13C, and Δ 47 measurements from proxies of past environments to proxies for certain biomineralisation strategies across space, time, and phylogeny among Bivalvia and other calcifying organisms. 相似文献
7.
Concentration and isotopic composition (δ 13C and δ 18O) of ambient CO 2 and water vapour were determined within a Quercus petraea canopy, Northumberland, UK. From continuous measurements made across a 36-h period from three heights within the forest canopy,
we generated mixing lines (Keeling plots) for δ a
13CO 2, δ a C 18O 16O and δ a H 2
18O, to derive the isotopic composition of the signal being released from forest to atmosphere. These were compared directly
with measurements of different respective pools within the forest system, i.e. δ 13C of organic matter input for δ a
13CO 2, δ 18O of exchangeable water for δ a C 18O 16O and transpired water vapour for δ a H 2
18O. [CO 2] and δ a
13CO 2 showed strong coupling, where the released CO 2 was, on average, 4 per mil enriched compared to the organic matter of plant material in the system, suggesting either fractionation
of organic material before eventual release as soil-respired CO 2, or temporal differences in ecosystem discrimination. δ a C 18O 16O was less well coupled to [CO 2], probably due to the heterogeneity and transient nature of water pools (soil, leaf and moss) within the forest. Similarly,
δ a H 2
18O was less coupled to [H 2O], again reflecting the transient nature of water transpired to the forest, seen as uncoupling during times of large changes
in vapour pressure deficit. The δ 18O of transpired water vapour, inferred from both mixing lines at the canopy scale and direct measurement at the leaf level,
approximated that of source water, confirming that an isotopic steady state held for the forest integrated over the daily
cycle. This demonstrates that isotopic coupling of CO 2 and water vapour within a forest canopy will depend on absolute differences in the isotopic composition of the respective
pools involved in exchange and on the stability of each of these pools with time.
Received: 21 March 1998 / Accepted: 10 December 1998 相似文献
8.
The tendency for mixed-isotope O 2 fragments to exhibit different stretching frequencies in asymmetric environments is examined with various levels of electronic
structure theory for simple peroxides and peroxyl radicals, as well as for a variety of monocopper–O 2 complexes. The study of the monocopper species is motivated by their relevance to the active site of galactose oxidase. Extensive
theoretical work with an experimental model characterized by Jazdzewski et al. ( J. Biol. Inorg. Chem. 8:381–393, 2003) suggests that the failure to observe a splitting between 16O 18O and 18O 16O isotopomers cannot be taken as evidence against end-on O 2 coordination. Conformational analysis on an energetic basis, however, is complicated by biradical character inherent in all
of the copper–O 2 singlet structures.
Electronic Supplementary Material Supplementary material is available for this article at . 相似文献
9.
Cotton ( Gossypium hirsutum L. cv. CS50) plants were grown at two levels of relative humidity (RH) and sprayed daily with abscisic acid (ABA) at four concentrations. Plants grown at lower humidity had higher transpiration rates, lower leaf temperatures and lower stomatal conductance. Plant biomass was also reduced at low humidity. Within each humidity environment, increasing ABA concentration generally reduced stomatal conductance, evaporation rates, superficial leaf density and plant biomass, and increased leaf temperature and specific leaf area. As expected, decreased stomatal conductance resulted in decreased carbon isotope discrimination in leaf material ( Δ 13C l). Plants grown at low humidity were more enriched in 18O than those grown at high RH, as theory predicts. Within each humidity environment, increasing ABA concentration increased oxygen isotope enrichment of leaf cellulose ( Δ 18O c) and whole‐leaf tissue ( Δ 18O l). Values of Δ 13C l and Δ 18O l predicted by theoretical models were close to those observed, accounting for 79% of the measured variation in Δ 13C l and 95% of the measured variation in Δ 18O l. Supporting theory, Δ 13C l and Δ 18O l in whole‐leaf tissue were negatively related. 相似文献
10.
Using both oxygen isotope ratios of leaf water (δ 18O L) and cellulose (δ 18O C) of Tillandsia usneoides in situ, this paper examined how short‐ and long‐term responses to environmental variation and model parameterization affected the reconstruction of the atmospheric water vapour (δ 18O a). During sample‐intensive field campaigns, predictions of δ 18O L matched observations well using a non‐steady‐state model, but the model required data‐rich parameterization. Predictions from the more easily parameterized maximum enrichment model (δ 18O L–M) matched observed δ 18O L and observed δ 18O a when leaf water turnover was less than 3.5 d. Using the δ 18O L–M model and weekly samples of δ 18O L across two growing seasons in Florida, USA, reconstructed δ 18O a was ?12.6 ± 0.3‰. This is compared with δ 18O a of ?12.4 ± 0.2‰ resolved from the growing‐season‐weighted δ 18O C. Both of these values were similar to δ 18O a in equilibrium with precipitation, ?12.9‰. δ 18O a was also reconstructed through a large‐scale transect with δ 18O L and the growing‐season‐integrated δ 18O C across the southeastern United States. There was considerable large‐scale variation, but there was regional, weather‐induced coherence in δ 18O a when using δ 18O L. The reconstruction of δ 18O a with δ 18O C generally supported the assumption of δ 18O a being in equilibrium with precipitation δ 18O (δ 18O ppt), but the pool of δ 18O ppt with which δ 18O a was in equilibrium – growing season versus annual δ 18O ppt – changed with latitude. 相似文献
11.
The ability to use δ 18O values of nitrous oxide (N 2O) to apportion environmental emissions is currently hindered by a poor understanding of the controls on δ 18O–N 2O from nitrification (hydroxylamine oxidation to N 2O and nitrite reduction to N 2O). In this study fertilized agricultural soils and unfertilized temperate forest soils were aerobically incubated with different 18O/ 16O waters, and conceptual and mathematical models were developed to systematically explain the δ 18O–N 2O formed by nitrification. Modeling exercises used a set of defined input parameters to emulate the measured soil δ 18O–N 2O data (Monte Carlo approach). The Monte Carlo simulations implied that abiotic oxygen (O) exchange between nitrite (NO 2?) and H 2O is important in all soils, but that biological, enzyme‐controlled O‐exchange does not occur during the reduction of NO 2? to N 2O (nitrifier‐denitrification). Similarly, the results of the model simulations indicated that N 2O consumption is not characteristic of aerobic N 2O formation. The results of this study and a synthesis of the published literature data indicate that δ 18O–N 2O formed in aerobic environments is constrained between +13‰ and +35‰ relative to Vienna Standard Mean Ocean Water (VSMOW). N 2O formed via hydroxylamine oxidation and nitrifier‐denitrification cannot be separated using δ 18O unless 18O tracers are employed. The natural range of nitrifier δ 18O–N 2O is discussed and explained in terms of our conceptual model, and the major and minor controls that define aerobically produced δ 18O–N 2O are identified. Despite the highly complex nature of δ 18O–N 2O produced by nitrification this δ 18O range is narrow. As a result, in many situations δ 18O values may be used in conjunction with δ 15N–N 2O data to apportion nitrifier‐ and denitrifier‐derived N 2O. However, when biological O‐exchange during denitrification is high and N 2O consumption is low, there may be too much overlap in δ 18O values to distinguish N 2O formed by these pathways. 相似文献
12.
The oxygen isotope composition of cellulose (δ 18O Cel) archives hydrological and physiological information. Here, we assess previously unexplored direct and interactive effects of the δ 18O of CO 2 (δ 18O CO2), nitrogen (N) fertilizer supply and vapour pressure deficit (VPD) on δ 18O Cel, 18O‐enrichment of leaf water (Δ 18O LW) and cellulose (Δ 18O Cel) relative to source water, and p exp x, the proportion of oxygen in cellulose that exchanged with unenriched water at the site of cellulose synthesis, in a C 4 grass ( Cleistogenes squarrosa). δ 18O CO2 and N supply, and their interactions with VPD, had no effect on δ 18O Cel, Δ 18O LW, Δ 18O Cel and p exp x. Δ 18O Cel and Δ 18O LW increased with VPD, while p exp x decreased. That VPD‐effect on p exp x was supported by sensitivity tests to variation of Δ 18O LW and the equilibrium fractionation factor between carbonyl oxygen and water. N supply altered growth and morphological features, but not 18O relations; conversely, VPD had no effect on growth or morphology, but controlled 18O relations. The work implies that reconstructions of VPD from Δ 18O Cel would overestimate amplitudes of VPD variation, at least in this species, if the VPD‐effect on p exp x is ignored. Progress in understanding the relationship between Δ 18O LW and Δ 18O Cel will require separate investigations of p ex and p x and of their responses to environmental conditions. 相似文献
13.
6-[ 18F]Fluoropyridoxal was synthesized by the flourination of a propylamine derivative of pyridoxal (pyridoxal Schiff base) with 18F-labelled acetylhypofluorite. Two different fluorinating agents, 5% F 2 in N 2 and acetylhypofluorite, were investigated with nonradioactive material. The evaluation of reactions in CH 3CN and chloroform showed CH 3CN to be the better solvent and CH 3COOF to be the better fluorinating reagent. The synthesis gave a radiochemical yield of about 18% (expressed at the end of synthesis) and required 35–40 min to complete. The specific activity of the final radiopharmaceutical at the end of the synthesis was about 25.9 GBq/mmol (700 mCi/mmol).The tissue distribution of 6-fluoropyridoxal in rat at 60 min is also reported. A large concentration in liver and kidney indicates that this radiopharmaceutical could be of special interest in the imaging of liver functions. The concentration in the brain might also allow in vivo PET imaging of the 6-(fluoropyridoxal) uptake if a high efficiency PET scanner is used. 相似文献
14.
The metabolism of 14C-labeled fatty acids and triacylglycerols was followed in intact germinating oil palm seedlings as well as in tissue slices. In the germinating seedling, the shoot contained a normal pattern of membrane fatty acids (mainly C 16, C 18:1, C 18:2) but the kernel contained about 68% C 12 and C 14 fatty acids. Haustorium fatty acids were intermediate between the two. [ 14C]Acetate was actively metabolized by shoot and haustorium slices but not so actively by the kernel. Approximately 9% to 17% was converted to water-soluble substances, 4% to 6% to CO 2, and 0.5% to 5.9% to lipids. The fatty acids synthesized in the shoot and haustorium were mainly C 16, C 18, and C 18:1 fatty acids but in the kernel about 18% to 32% of the 14C-fatty acids were C 12 fatty acids. [14C]Lauric acid was absorbed and metabolized by haustorium slices and by the haustorium in intact seedlings; it was partly esterified to triacylglycerols and also converted to water-soluble substances and insoluble tissue material. In contrast, tri-[14C]laurin was absorbed but not metabolized. The haustorium also absorbed other fatty acids but the longer chain (C16 and C18) fatty acids were not esterified or metabolized further. Preincubation of the haustorium with plant hormones or in the presence of kernel tissue did not alter its inactivity towards tri-[14C]laurin. When tri-[14C]laurin or [14C]lauric acid were injected into the seed or the shoot, there was no movement or radioactivity to other parts of the seedling. When injected into the shoot, but not into the seed, tri-[14C] laurin was hydrolyzed and partly metabolized to water-soluble substances. 相似文献
15.
The abundance and distribution of dissolved CH 4 were determined from 1987–1990 in Lake Fryxell, Antarctica, an amictic, permanently ice-covered lake in which solute movement
is controlled by diffusion. CH 4 concentrations were < 1 υM in the upper oxic waters, but increased below the oxycline to 936 μM at 18 m. Sediment CH 4 was 1100 μmol (1 sed) −1 in the 0–5 cm zone. Upward flux from the sediment was the source of the CH 4, NH 4
+, and DOC in the water column; CH 4 was 27% of the DOC+CH 4 carbon at 18 m. Incubations with surficial sediments indicated that H 14CO 3
− reduction was 0.4 μmol (1 sed) −1 day −1 or 4× the rate of acetate fermentation to CH 4. There was no measurable CH 4 production in the water column. However, depth profiles of CH 4, NH 4, and DIC normalized to bottom water concentrations demonstrated that a significant CH 4 sink was evident in the anoxic, sulfate-containing zone of the water column (10–18 m). The δ 13CH 4 in this zone decreased from −72 % at 18 m to −76% at 12 m, indicating that the consumption mechanism did not result in an
isotopic enrichment of 13CH 4. In contrast, δ 13CH 4 increased to −55 % at 9 m due to aerobic oxidation, though this was a minor aspect of the CH 4 cycle. The water column CH 4 profile was modeled by coupling diffusive flux with a first order consumption term; the best-fit rate constant for anaerobic
CH 4 consumption was 0.012 yr −1. On a total carbon basis, CH 4 consumption in the anoxic water column exerted a major effect on the flux of carbonaceous material from the underlying sediments
and serves to exemplify the importance of CH 4 to carbon cycling in Lake Fryxell. 相似文献
16.
Age-mediated deacetylation of hyaluronic acid and dermatan sulfate, and shift of sulfate ester configuration were indicated by infrared spectroscopy. Hyaluronic acid and the three dermatan sulfates (DS 18, DS 18 and DS 35), sequentially precipitated from adult skin with 18%, 28% and 35% ethanol, were analyzed at varying ages. At age 75 years, loss of infrared bands in the 1650-1600 cm −1 region, at 1380 cm −1 and 1320 cm −1 and appearance of a band at 1560 cm −1 were characteristic of hyaluronic acid and DS 35,·moreover, in DS 28 and DS 35 the intensities of the bands at 840 cm −1 and 860 cm − were, respectively, decreased and increased. A low intensity band in the 805-785 cm −1 region was observed in the spectra of DS 18 (19–35 years), DS 28 (70–80 years) and DS 35 (all ages). It intensified in DS 28 of the 80-years-olds. In the 75±5-year-old group. ninhydrin-positive material of hyaluronic acid and DS 35 increased, while reducing GlcNAc of hyaluronic acid decreased. The data demonstrated hyaluronic acid and DS 35 deacetylation and suggested a decrease of equatorial sulfates with infrared band at 840 cm −1 and an incrase of axial sulfates with band at 860 cm −1 in DS 28 and DS 35 of the 75±5-yearl-old set. Equatorial sulfates with band in the 805±785 cm −1 region apparently decreased in DS 18 after 35 years and increased in DS 28 of the oldest group. 相似文献
18.
Oxygen utilization is defined in this investigation as the terminal use of oxygen in respiration, i.e., the formation of water. A culture of Pseudomonas fluorescens was allowed to respire in an atmosphere of O 18. The production of H 2O 18 was measured during two test runs of 124 and 232 min each. During the first run, 0.505 mmole of H 2O 18 was produced. The second run produced 0.460 mmole of H 2O 18. H 2O 18 production took place throughout the course of each of the runs. 相似文献
19.
In this study, we synthesized 18F-ASu-BF 3, a close boramino acid analog of 5-[ 18F]fluoro-aminosuberic acid ( 18F-ASu), via 18F- 19F isotope exchange reaction and evaluated its potential for imaging with positron emission tomography (PET). 18F-ASu-BF 3 was stable in mouse plasma and taken up into PC3 prostate cancer cells via the system x C? amino acid transporter. The continuous use of isoflurane for anesthesia during dynamic imaging acquisition slowed down the excretion of 18F-ASu-BF 3 and enabled visualization of PC3 tumor xenografts in mice. In contrast, no tumor visualization was observed from static images of 18F-BF 3-ASu due to its rapid renal excretion mediated in part by the organic anion transporter. Our data indicate that the pharmacokinetics of amino acids could be altered after being converted into their boramino acid analogs. Therefore, care should be taken when using the boramino acid strategy to design and prepare 18F-labeled tracers for imaging amino acid transporters/receptors with PET. 相似文献
20.
Purpose[ 18F]Fluoromethylcholine ([ 18F]FMCH) is a radiopharmaceutical used in positron emission tomography (PET) imaging for the study of prostate, breast, and brain tumors. It is usually synthesized in cyclotron facilities where 18F is produced by proton irradiation of [ 18O]H 2O through 18O(p,n) 18F reaction. Due to the activation of target materials, the bombardment causes unwanted radionuclidic impurities in [ 18O]H 2O, that need to be removed during the radiopharmaceutical synthesis. Thus, the aim of this study is to quantify the radionuclide impurities in the 18F production process and in the synthesized [ 18F]FMCH, demonstrating the radionuclidic purity of this radiopharmaceutical. MethodsLong-lived radionuclide impurities were experimentally assessed using high-resolution gamma and liquid scintillation spectrometries, while short-lived impurities were monitored analyzing the decay curve of the irradiated [ 18O]H 2O with an activity calibrator. As spectrometric radionuclide library, a Geant4 Monte Carlo simulation of the 18F-target assembly was previously performed. Results3H, 52,54Mn, 56,57,58Co, 95m,96Tc, 109Cd, and 184Re were found in the irradiated [ 18O]H 2O, but no radionuclide was found in the non-irradiated [ 18O]H 2O neither in the final [ 18F]FMCH solution with an activity concentration greater than the minimum detectable activity concentration. A total impurity activity <6.2 kBq was measured in the irradiated [ 18O]H 2O, whereas a [ 18F]FMCH radionuclide purity >99.9999998% was estimated. Finally, the decay curve of the irradiated [ 18O]H 2O revealed a very low maximum of 13N activity (<0.03% of 18F) even immediately after the end of bombardment. ConclusionsThis study demonstrated the radionuclidic purity of [ 18F]FMCH according to the EU Pharmacopeia. 相似文献
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