title: Development and Design of a Single-Stage Cryogenic Modulator for Comprehensive Two-Dimensional Gas Chromatography.
abstract: A new liquid nitrogen-based single-stage cryogenic modulator was developed and characterized. In addition, a dedicated liquid nitrogen delivery system was developed. A well-defined restriction placed inside a deactivated fused silica capillary was used to increase the cooling surface area and provide very efficient trapping. At the same time, it enabled modulation of the carrier gas flow owing to changes in gas viscosity with temperature. Gas flow is almost unimpeded at the trapping temperature but reduced to nearly zero at the desorption temperature, which prevents analyte breakthrough. Peak widths for n-alkanes of 30-40 ms at half height were obtained. Most importantly, even the solvent peak could be modulated, which is not feasible with any commercially available thermal modulator. Evaluation of the newly developed system in two-dimensional gas chromatography (GC × GC) separations of some real samples such as regular gasoline and diesel fuel showed that the analytical performance of this single-stage modulator is fully competitive to those of the more complicated dual-stage modulators.
authors.affiliation: Department of Chemistry, University of Waterloo , 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.|Department of Pharmaceutical Chemistry, College of Clinical Pharmacy, University of Dammam , 31441, Dammam, Eastern Province, Kingdom of Saudi Arabia.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Mostafa
authors.affiliation: Department of Chemistry, University of Waterloo , 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Górecki