Splitter-based Non-cryogenic Artificial Trapping (SNAT): Novel modulation mechanism in comprehensive two dimensional gas chromatography

Abstract

Splitter-based non-cryogenic artificial trapping (SNAT) modulation approach in comprehensive two dimensional gas chromatography (GC × GC) was developed. The system employed semi-nonpolar/polar columns, a restrictor and a microfluidic Deans switch (DS) applying periodic multiple heartcuts (H/C) and several splitters with different dimensions located between the first (1D) column outlet and the DS. These splitters enabled artificial split-and-trap process consisting of 1) systematic pulse splitting, 2) split-pulse delay and 3) the pulse combination prior to 4) periodic selective H/C of the overlapped pulse. The interval between each H/C was herein defined as a new parameter called artificial modulation period (PAM). Methods to adjust sampling time (tsamp) and PAM were described with tsamp/PAM ratios equal to numbers of the splitters (nsplit). This was demonstrated for artificial modulation of a solvent mixture with nsplit = 4 and 8 as well as separation of lighter gas, lubricant and diesel samples using the PAM range of 0.23–4.57 min. Intraday and interday percentages of relative standard deviation (%RSD) of peak areas in repeated separations of the solvent mixture (n = 15) were within the range of 0.7–12% and 4–10%, respectively. The%RSD ranges for the 1D modulated times were 0–0.2% and 0–0.09%, respectively. The established approach enables artificial split-and-trap of highly volatile compounds without cryogen consumption and use of a long second dimensional (2D) column.