Decay correction

Procedures for pretreatment of soil samples and synthesis of sample benzene for 14C analysis had been described in Chen et al. (2002b). Sample benzene was often left for 3-4 weeks to allow any radon with half-life of 3.82 days that may be present to decay. 14C activity of the CgFL was then determined using a 1220-QUANTULUS ultralow-level liquid scintillation spectrometer manufactured by WALLAC Company, Sweden. The 14C analyses were conducted at the Guangzhou Institute of Geochemistry, CAS. Results are reported as A14C, in parts per thousand of the 14C/12C ratio from that of the standard (oxalic acid decay corrected to 1950) (Stuiver and Po-lach 1977), and corrected for bomb 14C (Chen et al. 2002b), where ... 

O Connor D. V., Ware W. R. and Andre J. C. Pouget J., Mugnier J. and Valeur B. (1989) (1979) Deconvolution of Fluorescence Decay Correction of Timing Errors in Multi-Curves. A Critical Comparison of Tech- frequency Phase/Modulation Fluoro-... 

For comparison, all the radiochemical yields (RCY) of labelled compounds are expressed in percentages from the cyclotron-produced labelled precursor. They are decay corrected from the end of bombardment (BOB) except when stated. 

A similar strategy, using a recently described PTC [158], was used to transform [2- F]fluoro-4-methoxy-benzylbromide into [2- F]fluoro-L-tyrosine (ee> 97%, 25% decay corrected, 100 min) (Scheme 26) [158b]. 

F]Fluoroacetate, a rodenticide, has been prepared in 24% yield (non-decay-corrected, in 70-90 min synthesis time) [242] from 0-mesylglycolate using [isFjtetrabutylammonium fluoride in the presence of tetrabutylammonium hydro geno carbonate. 

It was synthesised in 20-40% overall radiochemical yield (non-decay corrected) in less than 40 min. The radiochemical yield of the alkylation reaction of dimethylethanolamine with [ F]fluorobromomethane was greater than 90%. 

A/-[4-[(4-[ F]Fluorobenzylidene)amino-oxy]butyl]maleimide ([ F]FBABM) was synthesised in two steps, involving the preparation of 4-[ F]fluorobenzaldehyde (see Section 4.3.1.1), in an overall radiochemical yield of 35% in 60 min [267], whereas A/-[2-(4-[ F]fluorobenzamido)ethyl]maleimide ([ F]FBEM) was synthesised in three steps via 4-[ F]fluorobenzoic acid (see Section 4.3.1.1) in an overall radiochemical yield of 12% in 150 min [268]. Finally, based on the successful use of nucleophilic /leferoaromatic ort/io-radiofluorination in the pyridine series (see Section 4.3.2.1), 1-[3-(2-p F]fluoropyridin-3-yloxy)propyl]pyrrole-2,5-dione was prepared in 17-20% non-decay-corrected radiochemical yield in a three-step pathway taking less than 110 min [13,269]. These three reagents have been successfully coupled to peptides and proteins (>80% radiochemical yield in 10 min). 

A/-[3-(2-[ F]fluoropyridin-3-yloxy)-propyl]-2-bromoacetamide (p F]FPyBrA) was recently prepared by nucleophilic / eferoaromatic radiofluorination using a three-step radiochemical pathway and obtained in 20% overall non-decay-corrected yield in less than 85 min. In this reagent, the pyridinyl moiety carries the radioactive fluorine and the 2-bromoacetamide function ensures the alkylation of phosphorothioate monoester groups at the 3 - or 5 -end of a single-stranded oligonucleotide [18],... 

Yield. The Rb-82 content of 50 ml of eluate, decay corrected to end of elution, collected at 50 ml/min is measured in a Capintec CRC-17 dose calibrator using the potentiometer setting recommended by the manufacturer for Rb-82. While this datum is not as significant as the dynamic yield information obtained from measurement of elution profiles, it is valuable in preliminary development work and in monitoring the performance of a given unit through an extended use period. 

The 7Be disintegration rate also reached a maximum in the middle of the storms. In the second storm the 7Be maximum preceded the rainfall maximum. The 7Be activity began to decrease before the decay-corrected 38C1 and 39C1 activities. 

F]VUF 5000 was obtained in 23-34% radiochemical yield (decay corrected) within 3.5 hours and purified with HPLC. It was isolated with a radiochemical purity of > 99% and a specific activity of more then 2500 Ci/pmol [25], Biodistribution however showed a very low brain uptake after iv injection in the rat and so [1SF]VUF 5000 proved to be inappropriate for brain imaging with PET. 

F = fraction of total activity assigned to measured radiation D = decay correction for interval between time for which activity is determined and sample is measured... 

Ratio, adjusted for uranium amounts in sample, of net alpha and decay-corrected net beta-particle counting rate in Table 7.1 to Table 7.2 (alpha) (beta) ... 

Ratio of alpha particle and decay-corrected beta particle net count rates in Table 7.4 to Table 7.5 (alpha) (beta) cps... 

Step 4. Count each mounted filter with the same beta-particle detector as the samples in this experiment, Step 13, for 6,000 s. Calculate the counting efficiency, e, for 131I in Pdl2 by equation (10.1). Decay correction is for the interval between the time recorded on standard certificate and the time of counting. Record information in Data Table 10.3... 

Mesulergin 300, a selective ligand for the serotonin-2 receptor282 (related to a number of neurological diseases), has been labelled283 with nC in N(6) by reaction of N(6)-desmethyl-300 with nCH3I. The yield (decay corrected) was 40-50% after a synthesis time of 30 min. Up to 12 mCi of 300 have been prepared at specific activity 10 Ci mmol-1. 

The radiosynthesis of 323 in ca 15% radiochemical yield (decay-corrected) required 210 min from EOB. 

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