Alcohol ¹³C Analysis

Alcohol is analyzed for ¹³C using a Surveyor HPLC coupled to a Delta Plus isotope ratio mass spectrometer through a Finnigan LC Isolink interface (Thermo Electron Corp.).  Pure alcohols and beverages are analyzed through direct injection into the oxidation interface. In mixtures, compounds are separated on a HyperREZ Carbohydrate H+ column (8 x 300mm; Thermo, Cheshire, U.K.) at 65ºC using in a 5 mM sulfuric acid mobile phase. Flow rate is a constant 0.4 mL/min. After separation, the column eluent is mixed with sodium peroxidisulfate (0.8 M) and phosphoric acid (1.7 M), separately pumped at 30 µL/min. Individual compound peaks are then quantitatively oxidized to CO₂ as the mobile phase flows through an oxidation reactor at 99.9ºC. Each CO2 peak is transferred from aqueous phase to He carrier gas (2 mL/min) in a separation unit. Following water removal using a two-stage Nafion™ drier, the CO₂ peaks enter the IRMS through an open split. Delta ¹³C values are corrected using an ethanol reference calibrated against NIST standard reference materials.

References

Jochmann, M.A., Steinmann, D. , Stephan, M. , and Schmidt, T.C. 2009.  Flow injection analysis-isotope ratio mass spectrometry for bulk carbon stable isotope analysis of alcoholic beverages. Journal of Agric. and Food Chemistry 57:10489–10496.

Cabanero, A.I., Recio, J.L., and Ruperez, M. 2010. Simultaneous stable carbon isotopic analysis of wine glycerol and ethanol by liquid chromatography coupled to isotope ratio mass spectrometry. Journal of Agric. and Food Chemistry 58:722–728.