FIGURE 4. Percentage of stable [¹⁸F]FHBG found in urine samples of healthy volunteers 2.5 h after injection of [¹⁸F]FHBG tracer. [¹⁸F]FHBG elutes from anion exchange column at 6 min. This analysis shows that 82.94% ± 9.31% (n = 10) of total activity found in urine specimens was stable [¹⁸F]FHBG.