A conventional analytical apparatus for simultaneous determination of oxygen and nitrogen was modified by inserting a by-pass column filled with an appropriate amount of molecular sieve 5A into the gas flowing path. The extraction curve of oxygen could be fully separated from that of nitrogen when the measuring conditions were optimized. When high-purity potassium nitrate was employed as a certified material for the calibration, a linear relationship of the signal response was obtained up to the upper limit of nitrogen that the equipment could quantify. Using these optimized parameters for the measurement, analytical results of nitrogen in steel standard samples agreed to the corresponding guaranteed values.
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