Determination of Atmospheric Krypton and Xenon by Gas Chromatography-Mass Spectrometry in Direct Injection Mode
Abstract Volume concentration determination of atmospheric krypton and xenon is very important for krypton-85 and radioactive xenon isotopes monitoring. An injection set-up integrated adjustable quantity sample injection and quantitative dilution function was designed. The effects of electron impact (EI) source parameters on the sensitivity of MS detector were studied. Optimal values were as follows: ionization energy of 70 eV, emission current of 40 mA, cathode voltage of 27 mV, ion focus voltage of 85 mV and lens compensation voltage of 20 V. A GC-MS method for the determination of krypton and xenon in atmosphere without sample pretreatment was developed. Minimal detected concentrations for krypton and xenon were 3.3 × 10−8 (V/V) and 2.6 × 10−9 (V/V) respectively. Moreover, krypton and xenon concentrations in the ground level air were measured with the results of 1.1 × 10−6 (V/V) and 9.3 × 10−8 (V/V). The related combined standard uncertainties for krypton and xenon results were 2.38% and 3.15%, respectively.