AOAC 2019 First Action Methods

AOAC Official Method 2019.04 Alcohol Content in Kombucha Tea Headspace Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry First Action 2019

A. Apparatus ( a ) Analyses were done on 6890/5973N and 7890/5977C GC/MS systems (Agilent Technologies, Santa Clara, CA, USA). ( b ) The chromatographic separation in both systems was performed on a 30 m x 0.25 mm ID, 0.50 µm d f SUPELCOWAX 10 capillary column (MilliporeSigma, Bellefonte PA, USA) with helium carrier gas. ( c ) The SPME fiber used was fused silica, 100 µm polydimethylsiloxane (PDMS), 24 gauge, installed in an autosampler-style holder (MilliporeSigma, Bellefonte PA, USA). ( d ) SPME and injection were performed using an MPS autosampler with cooled agitator (Gerstel GmbH & Co. KG, Mϋlheim an der Ru hr, Germany). ( e ) Deionized water was obtained from a Barnstead Nanopure Diamond water system (ThermoFisher Scientific, Dubuque, IA, USA). ( f ) Quantitative data analysis was done using Mass Hunter Software (Agilent Technologies, Santa Clara, CA) and method validation parameters were calculated using Microsoft Excel. B. Reagents ( a ) 200 proof ethanol (99.5 % purity) was obtained from MilliporeSigma (St. Louis, MO, USA). ( b ) Anhydrous ethanol-d6 (99%) was obtained from Cambridge Isotope Laboratories (Andover, MA, USA) and MilliporeSigma (St. Louis, MO, USA). ( c ) Sodium chloride (99.5% purity), sodium phosphate-monobasic (99%), and sodium phosphate-dibasic (99%) were obtained from MilliporeSigma (St. Louis, MO, USA). ( d ) A .05 M phosphate buffer solution containing 25% w/v sodium chloride was prepared by dissolving 7 g of sodium phosphate dibasic and 25 g sodium chloride to a final volume of 1 L in water. The resulting solution was then adjusted to pH 7 with addition of sodium phosphate monobasic. ( e ) Alcohol calibration standards were prepared at concentrations of 0.10, 0.40, 0.80, 1.00, 1.50 and 2.00 percent alcohol by volume (%ABV) by direct dilution of aliquots of 200 proof ethanol