Comparison of Two Beer Samples by GCxGC-TOFMS

Introduction

The "COMPARE" feature, available in the Data Processing Method of ChromaTOF , is a single point calibration curve generated from a "Reference" sample, used to compare the Reference sample against a target sample. In this application note, the COMPARE feature will be used to compare two different samples of beer analyzed by SBSEGCxGC- TOFMS. The objective is to identify variations in twenty targeted compounds between the two samples. The Reference sample is of beer stored cold. The other sample is of the same beer that had been stored at an elevated temperature. For the remainder of this work, the sample from which the reference standard is made will be referred to as the "Reference" and the sample being compared to the reference standard will be called the "Sample". 

Instruments and Methods

In this study, measurements were made with a LECO Pegasus 4D GCxGC-TOFMS system. This system consists of an Agilent 6890 gas chromatograph equipped with a LECO dual-jet thermal modulator between the primary and secondary columns and a LECO Pegasus IV Time-of- Flight Mass Spectrometer (TOFMS) as a detector. For this study, the primary analytical column was a GERSTELMACH LTM 10.0 m x 0.18 mm ID x 0.20 μm df Rtx-5. The secondary column was a 1.00 m x 0.10 mm ID x 0.10 μm df DB-17ms and was housed in the GC oven. The temperature program for the LTM started at 30 C held for 2 minutes then ramped at 4 C/minute to 230 C and then held for 10 minutes. The column temperature offset for this study was +20 C. The modulator temperature offset for this study was +25 C. Helium was used as the carrier gas at a corrected constant flow of 1.5 mL/minute. The transfer line to the TOFMS consisted of the last 20 cm of the analytical column and was kept at 280 C.