GC/MS Analysis of Ethanol in Low Alcohol Beer on SUPELCOWAX® 10 after Headspace SPME using a 100 μm PDMS Fiber

GC/MS Analysis of Ethanol in Low Alcohol Beer on SUPELCOWAX® 10 after Headspace SPME using a 100 μm PDMS Fiber

Conditions

sample preparation sample equilibrated prior to extraction for 7 min at 40C, with agitation at 250 rpm
sample/matrix 4 mL of diluted low alcohol beer sample in 10 mL headspace vial
desorption process 250 C, 3 min, split 10:1
extraction headspace at 40C for 2 min, agitation at 250 rpm
SPME fiber Pk/3 SPME Assy, 100 µm, PDMS FS 24 ga Auto (Red) (57301)
column SUPELCOWAX 10, 30 m x 0.25 mm I.D., 0.25 µm (24079)
oven 40 C (5 min), 8 C/min to 70 C, 20 C/min to 250 C, held for 5 min
carrier gas helium, 1 ml/min constant flow
injection split, 10:1
liner 0.75 mm I.D. SPME
inj. temp. 250 C
detector MSD
MSD interface 250 C
scan range m/z 25-300

Description

Analysis Note Traditional methods for determination of alcohol in beverages include specific gravity and gas chromatography (GC). Specific gravity may not be able to accurately measure levels in beverages with low alcohol content, below 1%. GC is a better approach because it does not have this limitation. However, direct injection of samples containing sugars or other nonvolatile matrix components can foul the GC instrument. This drawback of GC can be overcome by sampling the headspace over the sample using solid phase microextraction (SPME), The method shown here was developed specifically for the determination of ethanol in low alcohol content samples, and was used to analyze a reference material of low alcohol beer. The sample had a certified value of 0.505% alcohol by volume (% ABV). Using headspace SPME, the average value measured was 0.495% ABV, representing 97% accuracy.
Featured Industry Food and Beverages
Legal Information SUPELCOWAX is a registered trademark of Sigma-Aldrich Co. LLC
Other Notes SPME Sample pretreatment: Dilute 400 uL of sample to 4 mL with 0.1M sodium phosphate buffer ( pH 7) containing 25% NaCl
suitability application for SPME, application for GC/MS

Materials

     
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