Quantifying Prenylated Hop Phenols

β-Glucuronidase and arylsulfatase were purchased from Sigma-Aldrich (St. Louis, MO). Formic acid (LC-MS grade) was purchased from Thermo Scientific (Rockford, IL), and methanol and acetonitrile (LC-MS grade) were purchased from VWR (Radnor, PA). Water was prepared using an ElgaPurelab Ultra (Siemens Water Technologies, Woodridge, IL) water purification system. Prenylated hop phenols were prepared from hops at the University of Illinois at Chicago/National Institutes of Health (UIC/NIH) Center for Botanical Dietary Supplements Research (Chicago, IL), structures were confirmed using high resolution mass spectrometry and NMR, and the purities were >95% by HPLC as described previously.^{14 (link)} Caffeine, [trimethyl-¹³C₃]-Caffeine, tolbutamide, dextromethorphan, [methyl-d₃]-dextromethorphan, alprazolam, and [phenyl-d₅]-alprazolam were purchased from Sigma-Aldrich (St. Louis, MO), and [butyl-d₉]-4-hydroxy-tolbutamide was purchased from Toronto Research Chemicals (Toronto, Canada). Serum from individual donors that was free of all probe substrates was purchased from Innovative Research (Novi, MI).