PT - JOURNAL ARTICLE AU - Trump, David AU - Reichert, Zachary TI - A simple test for tetrabutylammonium in 18F-FLT DP - 2010 May 01 TA - Journal of Nuclear Medicine PG - 1461--1461 VI - 51 IP - supplement 2 4099 - http://jnm.snmjournals.org/content/51/supplement_2/1461.short 4100 - http://jnm.snmjournals.org/content/51/supplement_2/1461.full SO - J Nucl Med2010 May 01; 51 AB - 1461 Objectives Develop a simple test for tetrabutylammonium (TBA) in 18F-FLT. Methods Tetrabutylammonium hydroxide was dissolved in water/or 18F-FLT solution to achieve 31, 63, 125, 250, 500, and 1000 μg/mL concentrations. Prepared solutions and 18F-FLT final product (2 μL) were spotted on TLC plates and developed in 10% ammonium hydroxide (in methanol) to allow the eluent to cover the spots. The strips were removed and quickly developed in iodine vapor, removed, and visually inspected. Samples of each solution were also analyzed by HPLC. Results TBA in water shows a very light spot at 31 μg/mL which continues to increase in color, size, and intensity with increasing concentrations up to 1000 μg/mL, where the color is very dark. Corresponding HPLC analysis of the same solutions showed a linear relationship between conductivity peak area and TBA concentration. The 18F-FLT samples spiked with TBA showed color, size, and intensity increases for the spots in proportion to increasing concentration up to 1000 μg/mL. HPLC analysis also showed a corresponding relationship between conductivity peak area and TBA concentration for the spiked 18F-FLT samples (R-squared >0.999). In addition, the test spots from 18F-FLT matrix spiked with TBA are similar in color, size, and intensity as corresponding solutions prepared from TBA in water, indicating that the 18F-FLT final product solution does not interfere with the test. All color-spots were visually distinguishable in color/size/intensity from adjacent spots of either half or twice the TBA concentration. Color-spot testing of the 18F-FLT final product initially revealed a very dark spot. When the 18F-FLT final product was prepared without citrate buffer, the spot intensity appeared to be between 31 μg/mL and 63 μg/mL. HPLC analysis of the 18F-FLT sample estimated the TBA content to be 36 μg/mL. Conclusions This test is adequate as a color-spot test for routine testing of TBA in water or the prepared 18F-FLT product