NOVELTY - An apparatus comprises a first gas chromatograph (108) including a fluid inlet, a fluid outlet, and a first temperature control; and a controller (126) coupled to the first temperature control, where the controller includes logic to apply a first temperature profile to the first temperature control to heat and/or cool the first gas chromatograph.    USE - For time-domain separating chemical from fluid (claimed); and for gas analysis in point-of-care medical applications which is used in detecting the presence and concentration of chemicals in the gas, and determining the presence of dangerous substances incompatible with human presence, such as methane, carbon monoxide or carbon dioxide in a mine.    ADVANTAGE - The apparatus and gas analysis system utilizes miniaturized gas chromatography column (GC)/micro-GC columns, which can be cascaded with different coating materials for gas separation analysis. The micro-GCs are small in size and thus can be promptly cooled down to sub-zero temperature with a simple small cooling device, which cannot be achieved using traditional bulky GC unless liquid nitrogen is used. With simple, fast, and direct micro-GC cooling, direct column focusing effect can be achieved, which sharpens the analyte spectrum and improves the column separation power. The direct fast GC cooling on micro-GC with simple cooling device allows the possibility of achieving spectrum sharpening without using liquid nitrogen, and also improves the detection limit, and implements a portable gas analysis system with improved system resolution and detection limit. The time-domain separation performed in gas chromatograph enhances the accuracy and sensitivity of micro-electro-mechanical (MEMS) detection array, as it prevents numerous chemicals from entering the detection array at the same time and thus prevents cross-contamination and potential interference in the sensors within the array.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a gas analysis system (100) comprising a substrate (102), a gas chromatograph having a fluid inlet and at least one fluid outlet and being mounted to the substrate, where the gas chromatograph comprises a first gas chromatograph having a first temperature control, at least one detector array (110) having a fluid inlet and a fluid outlet and being mounted to the substrate, where the fluid inlet of each of the detector array is fluidly coupled to a corresponding one of the fluid outlet of the cascaded gas chromatograph, a control circuit coupled to the cascaded gas chromatograph and to the detector array, where the control circuit includes logic to apply a first temperature profile to the first temperature control to heat and/or cool the first gas chromatograph, and where the control circuit can communicate with the gas chromatograph and with the detector array, and a readout circuit coupled to the detector array and to the control circuit, where the readout circuit can communicate with the control circuit and the detector array; and    (2) a process for time-domain separating at least one chemical from a fluid, involving injecting a fluid including chemicals into a gas chromatograph comprising a first gas chromatograph having a first temperature control, applying a first temperature profile to the first temperature control to heat and/or cool the first gas chromatograph, detecting each of the time-domain-separated chemicals using at least one sensor in at least one detector array coupled to the gas chromatograph, and processing signals from each sensor in the detector array to determine the presence and concentration of each chemical.    DESCRIPTION OF DRAWING(S) - The figure shows a side elevation drawing of a gas analysis device.    Gas analysis system (100)    Substrate (102)    Gas chromatograph (108)    Detector array (110)    Controller (126)