Three different concentrations of moxifloxacin-90 μg/mL, 100 μg/mL, and 110 μg/mLwere prepared from the standard stock solution. The sample preparation method is described in section 1.3 of the SI. Stock Placebo and secondary placebo were also prepared as described in section 1.4 of the SI. Three replicates of each of these three dilutions were injected, and the % recovery was calculated. The following formula was used to determine the % recovery.