Although samples were in a hot reflux for a long time at 85℃ in the experiment, and 5? molecular sieve of the adsorbed s尽管实验过程中样品经过85℃长时间加热回流及吸附样品的5?分子筛用氢氟酸酸化处理，但实验结果经仪器检测，证明该方法对正构烷烃碳同位素值影响因素不大。