Display Settings:


Send to:

Choose Destination
Nucl Med Biol. 2011 Nov;38(8):1129-34. doi: 10.1016/j.nucmedbio.2011.05.008. Epub 2011 Jul 8.

Improved detection and measurement of low levels of [18F]fluoride metabolized from [18F]-labeled pyrimidine nucleoside analogues in biological samples.

Author information

  • 1Department of Experimental Diagnostic Imaging, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.



It is important to identify all circulating metabolites, including free fluoride, for accurate pharmacokinetic modeling of [(18)F]-labeled radiotracers. We sought to determine the most efficient method to detect and quantify low levels of free [(18)F]fluoride in biological samples.


Low levels of [(18)F]fluoride were analyzed using two methods: (A) an ion-exchange cartridge and gamma counting, and (B) radio-HPLC, to compare the detection limits of these two analytical methods. Twenty microliters of [(18)F]fluoride solution was loaded onto an ion-exchange cartridge, then eluted with 20% MeCN/water (5 ml) and radioactivity trapped in the cartridge counted on a gamma counter. [(18)F]Fluoride was also determined in plasma and urine from mice injected with [(18)F]-labeled thymidine analogues using Method A.


The detection sensitivity of Method A was 9.4-fold higher than that of Method B (0.075±0.004 vs. 0.71±0.02 nCi). With Method A, [(18)F]fluoride was determined in plasma for [(18)F]FLT, [(18)F]FMAU, [(18)F]FEAU and N(3)-[(18)F]FPrT as 1.4±0.31% (n=4), 0.17±0.49% (n=3), 4.88±1.62% (n=3) and 12.94±0.48% (n=4), respectively. The amount of [(18)F]fluoride determined in the urine was 11.49±1.60% (n=4) from [(18)F]FLT, 5.36±2.34% (n=3) from [(18)F]FMAU, 13.57±1.96% (n=3) from [(18)F]FEAU and 11.19±1.98% (n=4) from N(3)-[(18)F]FPrT.


Low levels of [(18)F]fluoride in biological samples can be detected and quantified using an ion-exchange cartridge and gamma counting. This methodology is simple, accurate and superior to the standard use of radio-HPLC on a C(18) column for metabolite analysis, and it should be useful in pharmacokinetic modeling for animal imaging studies using an [(18)F]-labeled radiotracer and PET.

Copyright © 2011 Elsevier Inc. All rights reserved.

[PubMed - indexed for MEDLINE]
Free PMC Article

Images from this publication.See all images (3)Free text

Figure 1
Figure 2
Figure 3
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science Icon for PubMed Central
    Loading ...
    Write to the Help Desk