Optimization of Static Head-Space Gas Chromatography - Mass Spectrometry-Conditions for the Determination of Benzene, Toluene, Ethyl benzene, Xylene, and Styrene in Model Solutions

A method was developed and validated for the analysis of benzene, toluene, ethylbenzene, xylene (BTEX), and styrene in sea water samples using gas chromatography-mass spectrometry (GC-MS) with static headspace extraction. To carefully characterize the performance of this method, several factors affecting the parameters were studied in detail, such as the heating procedure, loop filling time, equilibrium temperature, the sample dilution ratio, equilibrium, and injection times. The optimized conditions are as follows: 1)the heating procedure, 50°C for 4 min, then increased to 170°C at 15°C min-1, 2) equilibrium temperature, 60°C, 3) equilibrium time, 5 min, and 4) injection time 0.5 min. Under the optimized conditions, the linear equations were obtained in the concentration range of 10 - 50 μg L-1 with good correlation coefficient values. The limits of detection were 1.8 - 3.3 μg L -1 . The recoveries at the spiked level of 20 μg L -1 BTEX and styrene ranged from 97% - 103% with the relative standard deviations were (RSD, n=3) 1.0% - 7.6%.