Aspects on the Use of Headspace GC On-Column Injections in Flavor Research

The volatiles of birch syrup and ripening bananas are analyzed by static and dynamic headspace chromatography, respectively. The gaseous samples are introduced into the gas chromatographic (GC) system by on-column injection and band cryofocusing, using an appropriate coolant. Seven birch syrup volatiles are studied under different volumes of gaseous injections, ranging from 0.03 to 8.0 mL. The linearity between GC response and sample size is good, with correlation coefficients (r) ranging from 0.993 to 0.999. Duplicability of an internal standard (methyl pentanoate), used to monitor changes during sample preparation and GC injection of volatiles from ripening bananas, varies with an RSD of less than 10% during an eight-day period. Main guidelines for efficient and reproducible headspace on-column injections are given.