A miniature closed-loop gas chromatography system.This paper reports the characterization of a miniaturized circulatory column system that is capable of magnifying the effective column length by forming a circulatory loop with chip-scale columns, thus ultimately achieving high-efficiency target separation. 
A miniature closed-loop gas chromatography system
The circulatory column system is composed of a tandem of 25 cm microcolumns and six valves for fluidic flow control in order to enable chromatographic separation in circulatory motions while requiring only 5.5 kPa of pressure, which current micropumps are currently capable of supplying. 
The circulatory column system