HIGH-SPEED GAS CHROMATOGRAPHY AS AN IMPROVED CHEMICAL INSTRUMENT

GAS CHROMATOGRAPHY IS ONE OF THE MOST WIDELY USED METHODS FOR THE CHEMICAL ANALYSIS OF ORGANIC COMPOUNDS. THE METHOD HAS BROAD APPLICABILITY, A VERY LARGE CONCENTRATION RANGE, AND EXCELLENT PRECISION AND ACCURACY. HOWEVER, IT IS QUITE SLOW REQUIRING SEVERAL MINUTES OR MORE PER ANALYSIS USING CONVENTIONAL INSTRUMENTATION AND TECHNIQUES. BY THE USE OF SHORT CAPILLARY SEPARATION COLUMNS OPERATED AT UNUSUALLY HIGH GAS VELOCITIES, ANALYSIS TIMES CAN BE REDUCED TO A FEW SECONDS IN MANY CASES. HOWEVER, OPERATION IN THIS TIME DOMAIN REQUIRES THE DEVELOPMENT OF HIGH-SPEED INLET SYSTEMS TO OBTAIN SUFFICIENTLY NARROW SAMPLE BAND WIDTHS. IN ADDITION, OPERATION AT VERY HIGH SPEED RESULTS IN SIGNIFICANT LOSS OF RESOLUTION. RESEARCHERS ARE DEVELOPING A HIGH-SPEED GAS CHROMATOGRAPHY INSTRUMENT THAT USES A CRYOFOCUSSING INLET SYSTEM CAPABLE OF PRECONCENTRATING A VAPOR SAMPLE AND INTRODUCING IT TO THE SEPARATION COLUMN ASA VERY NARROW PLUG. TO COMPENSATE FOR THE LOSS IN RESOLUTION, THE INSTRUMENT USES TANDEM ENSEMBLES OF CAPILLARY COLUMNS HAVING DIFFERENT STATIONARY PHASES. BY DIFFERENTIALLY ADJUSTING THE GAS FLOW RATES OR TEMPERATURES OF THE INDIVIDUAL COLUMNS, SELECTIVITY CAN BE ADJUSTED FOR SPECIFIC APPLICATIONS. ANALYSIS TIMES OF A FEW SECONDS SHOULD BE ACHIEVED.