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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 suitable for GC/MS, suitable for solid phase microextraction (SPME)

Materiais

Fibra para SPME

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Suporte de fibra para SPME

for use with CTC CombiPAL and Gerstel MPS2

Padrão

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Ethanol-d6

anhydrous, ≥99.5 atom % D

Álcool etílico, puro

200 proof, anhydrous, ≥99.5%

acessório

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Inlet Liner, Direct (SPME) Type, Straight Design (unpacked)

pkg of 1 ea

Headspace vial, screw top, rounded bottom (vial only)

volume 10 mL, clear glass vial, thread for 18, O.D. × H 22.5 mm × 46 mm, pkg of 100 ea

Tampa de rosca magnética para frascos de headspace, rosca de 18 mm

PTFE/silicone septum (white PTFE/tranparent blue silicone), septum thickness 1.3 mm, pkg of 100 ea

Molded Thermogreen® LB-2 Septa, with injection hole

diam. 11 mm, pkg of 50 ea

reagente

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Fosfato de sódio

ReagentPlus®, ≥99.0%

Fosfato de sódio

ReagentPlus®, ≥99.0%

teste de proficiência

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Beer (EtOH, low level)

BCR®, certified reference material

CONDITIONS

sample/matrix

4 mL of diluted low alcohol beer sample in 10 mL headspace vial

SPME fiber

Pk/3 SPME Assy, 100 μm, PDMS FS 24 ga Auto (Red) (57301)

extraction

headspace at 40°C for 2 min, agitation at 250 rpm

desorption process

250 °C, 3 min, split 10:1

sample preparation

sample equilibrated prior to extraction for 7 min at 40°C, with agitation at 250 rpm

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

inj. temp.

250 °C

detector

MSD

MSD interface

250 °C

scan range

m/z 25-300

carrier gas

helium, 1 mL/min constant flow

injection

split, 10:1

liner

0.75 mm I.D. SPME

Descrição

Nota de análise

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.

Outras notas

SPME Sample pretreatment: Dilute 400 uL of sample to 4 mL with 0.1M sodium phosphate buffer ( pH 7) containing 25% NaCl

Informações legais

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