Comprehensive two-dimensional gas chromatography(GC×GC) is a modern technique that passes all sample components through two different(orthogonal) capillary columns.Separation is achieved by coupling a gas chromatography separation in the first and second column via sophisticated interface(modulator),which is a piece of hardware that transfers effluent from the exit of the primary column to the head of the secondary column as a repetitive series of external pressure pulses.