title: Development of a Method for the Quantitation of Three Thiols in Beer, Hop, and Wort Samples by Stir Bar Sorptive Extraction with in Situ Derivatization and Thermal Desorption-Gas Chromatography-Tandem Mass Spectrometry.
abstract: A method for analysis of hop-derived polyfunctional thiols, such as 4-sulfanyl-4-methylpentan-2-one (4S4M2Pone), 3-sulfanylhexan-1-ol (3SHol), and 3-sulfanylhexyl acetate (3SHA), in beer, hop water extract, and wort at nanogram per liter levels was developed. The method employed stir bar sorptive extraction with in situ derivatization (der-SBSE) using ethyl propiolate (ETP), followed by thermal desorption and gas chromatography-tandem mass spectrometry (TD-GC-MS/MS) with selected reaction monitoring (SRM) mode. A prior step involved structural identification of the ETP derivatives of the thiols by TD-GC-quadrupole-time-of-flight mass spectrometry with parallel sulfur chemiluminescence detection (Q-TOF-MS/SCD) after similar der-SBSE. The der-SBSE conditions of the ETP concentration, buffer concentration, salt addition, and extraction time profiles were investigated, and the performance of the method was demonstrated with spiked beer samples. The limits of detection (LODs) (0.19-27 ng/L) are below the odor threshold levels of all analytes. The apparent recoveries at 10-100 ng/L (99-101%) and the repeatabilities [relative standard deviation (RSD) of 1.3-7.2%; n = 6] are also good. The method was successfully applied to the determination of target thiols at nanogram per liter levels in three kinds of beer samples (hopped with Cascade, Citra, and Nelson Sauvin) and the corresponding hop water extracts and wort samples. There was a clear correlation between the determined values and the characteristics of citrus hop aroma for each sample.
authors.affiliation: †GERSTEL K.K., 1-3-1 Nakane, Meguro-ku, Tokyo 152-0031, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Ochiai
authors.affiliation: †GERSTEL K.K., 1-3-1 Nakane, Meguro-ku, Tokyo 152-0031, Japan.
authors.forename: Kikuo
authors.initials: K
authors.lastname: Sasamoto
authors.affiliation: ‡Asahi Breweries, Limited, 1-21 Midori 1-chome, Moriya-shi, Ibaraki 302-0106, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Kishimoto
mesh_terms: D001515:Beer / Q000032:analysis*; D005503:Food Additives / Q000737:chemistry* / Q000302:isolation & purification; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D027582:Humulus / Q000737:chemistry*; D020902:Hypericum / Q000737:chemistry*; D009812:Odorants / Q000032:analysis; D052616:Solid Phase Extraction / Q000379:methods*; D013438:Sulfhydryl Compounds / Q000737:chemistry* / Q000302:isolation & purification*; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D005503:Food Additives; D013438:Sulfhydryl Compounds
keywords: GC−MS/MS; beer; hops; in situ derivatization; polyfunctional thiol; stir bar sorptive extraction (SBSE); wort