Determination of low levels of methanol and ethanol in licorice extract by large volume injection head-space GC

Abstract

A large volume injection head-space GC method was established for measuring low levels of residual methanol and ethanol in licorice extract used as a food additive. A vial was kept at 50°C in the oven of the head-space sampler. Injection of the head-space gas for 0.75 min into a Poraplot Q GC column with a initial oven temperature of 35°C, enabled the determination of low levels (5 μg/g) of methanol and ethanol. The standard deviations for five rounds of analysis of methanol and ethanol in licorice extracts were between 0.82 and 2.97. Methanol was found in 6 samples out of 9 collected in 1999, at concentrations exceeding 50 μg/g, the limit set by the Japanese Government, established in 1999 and coming into force on April 1, 2000. The highest concentration reached 10,000 μg/g. Methanol at a concentration exceeding 50 μg/g was found in 2 out of 9 samples collected in 2000. The highest concentration was 270 μg/g.