P-19
Separation & identification of stereoisomers of isomerized alpha-acid derivatives by HPLC/DAD & electrospray HPLC/MS/MS
Presenter: Patrick Ting, Miller Brewing Company
Co-Authors: Susan Kay and David Ryder, Miller Brewing Company

The composition of isomerized hop products is of importance for the bitterness, foam, and flavor stability of beer. A simple high-performance liquid chromatography/photodiode array detector (HPLC/DAD) using a 100 × 4.5 mm C-18 column and an aqueous methanol buffer solution can rapidly resolve cis- and trans-stereoisomers, and analogs of iso-alpha-acids, rho-iso-alpha-acids, tetrahydroiso-alpha-acids, and hexahydroiso-alpha-acids. A versatile electrospray HPLC/MS/MS demonstrates the ability to identify the composition of isomerized hop derivatives using both positive (M+H and M+Na) and negative (M-H) ion modes.

Patrick Ting earned his Ph.D. degree in organic chemistry from University of North Texas and post-doctoral at Southwestern Medical School, University of Texas. He is a member of the International Subcommittee for Isomerized Hop Alpha-Acids Standards. He has been working in hop research and development at Miller Brewing Company since 1978.