Novel methods for the quantification of toxic, residual phase transfer catalyst in fluorine-18 labeled radiotracers

David Blevins, Grant H. Rigney, Michael Y. Fang, Murthy Akula, Dustin Osborne

Research output: Contribution to journalArticle

Abstract

Introduction: Fluorine-18 labeled radiopharmaceuticals undergo quality control testing for residual phase-transfer-catalyst content. The almost universally used quality-control test is a silica plate spot-test comparison of the radiopharmaceutical beside a 50-ppm standard. Once developed by staining, the radiopharmaceutical spot must be of equal or less intensity to pass the test. There is currently a need for a quantitative, inexpensive, and less subjective quality control method that allows the automatic incorporation of the acquired measurement directly into electronic batch reports. Results: In the developed method, a resazurin test solution is mixed with an aliquot of the radiopharmaceutical analyte along with dichloromethane (DCM). The mixture is vortexed. The potassium resazurin-phase transfer catalyst complex solubilizes into the DCM imparting a blue color. The organic layer is then removed for analysis. Three measurement methods were utilized: visual colorimetry against pre-prepared standards, spectrophotometric measurement of transmittance, and electrical conductance. A simple prototype spectrophotometer and an electrical test cell were constructed to acquire data. Sodium Resazurin dye was found to be a suitable test chromophore for residual phase transfer catalyst analysis of aqueous solutions. Quantitative spectrophotometric measurements are possible in the 0–100-ppm range (18-crown-6) and 0–150-ppm range (Kryptofix® or tetrabutylammonium). Electrical resistance measurements of the phase transfer-catalyst resazurin complex in DCM are also a viable method, allowing quantitative phase transfer catalyst measurements in the 0–100-ppm range. Conclusion: The methodologies developed are more quantitative alternatives to the current spot-test method. The spectrophotometric method was determined to be the most accurate method.

Original languageEnglish (US)
Pages (from-to)41-48
Number of pages8
JournalNuclear Medicine and Biology
Volume74-75
DOIs
StatePublished - Jul 1 2019

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Fluorine
Poisons
Radiopharmaceuticals
Methylene Chloride
Quality Control
Colorimetry
Electric Impedance
Silicon Dioxide
Potassium
Coloring Agents
Color
Sodium
Staining and Labeling
resazurin

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

Cite this

Novel methods for the quantification of toxic, residual phase transfer catalyst in fluorine-18 labeled radiotracers. / Blevins, David; Rigney, Grant H.; Fang, Michael Y.; Akula, Murthy; Osborne, Dustin.

In: Nuclear Medicine and Biology, Vol. 74-75, 01.07.2019, p. 41-48.

Research output: Contribution to journalArticle

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