Recent advances in modulator technology for comprehensive two dimensional gas chromatography.

Abstract One of the greatest advancements in the field of gas chromatography (GC) has been the development of comprehensive two-dimensional gas chromatography (GC × GC). As the field of GC evolved from one-dimensional gas chromatography (1D-GC) to heart cutting (GC–GC), followed by the advent of GC × GC, the critical component at the center of this evolution has been the interface between the separation columns. The interface, referred to as the modulator for GC × GC, links the primary and secondary columns. This review covers the evolution of modulator systems from the founding of GC × GC in 1991 by Liu and Phillips, while focusing on the last six years. Since its inception, modulators have evolved into two distinct categories: thermal, and valve-based. The advantages and shortcomings of each category will be covered. Recent developments in the research, development, and commercialization of these various modulators is provided, with a glimpse into future modulator designs. Highlights • The past six years of GC × GC modulator advances are highlighted. • Two classes of modulators are discussed and compared: thermal and valve-based. • Valve-based modulation includes differential flow and flow diversion modulation. • Cryogen free thermal modulation is reviewed, contrasted with cryogen based systems. • Recent advances have allowed valve-based modulation periods as fast as 50 ms. [ABSTRACT FROM AUTHOR]