“Just shoot”—Quick and easy determination of hop iso-alpha-acids in beer

Analytical Session
Michael Heidorn, Thermo Fisher Scientific, Dornierstr. 4, 82110 Germering, Germany
Co-author(s): Markus Martin and Frank Steiner, Thermo Fisher Scientific, Germering, Germany; Rainer Bauder, Thermo Fisher Scientific, Chelmsford, MA, USA

ABSTRACT: Sample preparation is a crucial point in the workflow of beer analysis, especially during the brewing process where very complex matrices form the basic samples. Various sample preparation techniques are used to remove the beer matrix or enrich analytes of interest, with solid-phase extraction (SPE) being commonly used when HPLC is applied for analysis. Typically SPE is performed manually, thus causing a significant bottleneck as well as error source in laboratory workflows. Furthermore, samples need to be analyzed in time due to the ongoing process in the brew kettle. However, conventional analysis takes about an hour due to sample pretreatment steps, a manual SPE procedure, and RP-HPLC separation. An automation of this sample cleanup and analyte enrichment process eliminates all the issues described above, while the high-speed capabilities of UHPLC technology can significantly reduce the time required for chromatographic separation. Hence, direct injection of untreated beer samples becomes feasible, ensuring higher confidence in the analytical result and higher throughput by an unattended operation. In this presentation, the UHPLC separation of hop iso-alpha-acids in beer with an automated on-line SPE solution is demonstrated. An untreated beer sample is injected directly, all SPE steps are performed automatically, and the whole analysis lasts only 9 min. Thus, no manual sample pretreatment is needed, and the result of the high-speed separation reflects the content of iso-alpha-acids in the beer virtually in real time. Using this automated on-line SPE RP-UHPLC approach, the bitterness, foam, and stability of a beer can be controlled in a quick and easy way.

Michael Heidorn, born in 1980, completed an apprenticeship as a chemical laboratory assistant at Honeywell Specialty Chemicals GmbH, Seelze, Germany, and thereafter worked for the Research and Development Department of this company. Afterward, he studied analytical chemistry at the University of Applied Science in Luebeck, Germany. He completed his diploma thesis on the influence of frictional heating on column efficiency in UHPLC at the Research and Development Department of Dionex-Softron GmbH, now part of Thermo Fisher Scientific, and obtained a graduate chemical engineer degree. He then began working as a solution specialist in the HPLC Marketing Department of Thermo Fisher Scientific.