The rapid growth of the biofuels industry resulted in new research needs in chemical analysis. Methods for screening and quantification of impurities resulting from changes in feedstock, process and purification are needed. Direct sample injection methods are often not sensitive for lower concentrations. This research, developed an analytical method to simultaneously quantify fermentation volatile by‐products in industrial corn‐based ethanol. These include acetaldehyde, ethyl vinyl ether, 1,1‐diethoxyethane, isoamyl alcohol, isoamyl acetate, styrene, 2‐pentylfuran, ethyl hexanoate, ethyl octanoate, and ethyl decanoate. Headspace solid‐phase microextraction (SPME) coupled with gas chromatography–mass spectrometry (GC–MS) and GC‐FID were used. The effects of SPME coating, concentration, time, and salting out were tested. The optimized method used Carboxen/PDMS 85 µm coating with 10% (v/v) ethanol, 20 s headspace extraction, and no salt addition. The method had values of R2 between 0.93 and >0.99 and relative standard deviations between 0.10 and 11.96%. The method detection limits were between 9.5 × 10−4 to 9.7 × 10−8mol/L.This is one of the most comprehensive quantification methods for volatile impurities in raw ethanol to date. This new method was used to quantify 10 prevalent impurities in corn‐based industrial ethanol.
Available at: http://works.bepress.com/somchai_rice/19/