Abstract: Active fractions were extracted from series petroleum sulfonates by extraction and back－extraction method，the equivalent weight distribution of them were analyzed by ESI－MS spectrum and the average equivalent weight could be calculated，as well as gas－phase osmotic method was conducted to determine the average relative molecule mass of their oleophylic groups which were obtained by desulfonation．The interfacial tension of oil／water system respectively consisted of series petroleum sulfonates or their active fractions were measured by rotated dropping method．The results show that the difference of the equivalent weight distribution mainly existed in the low and high equivalent weight section，and the one which has properly hydrophile－lipophile balance for the complementation of molecule structure benefiting from broad equivalent molecule weight distribution，its oil／water system can obtain the ultralow interfacial tension．

Key words: Petroleum sulfonates , Active fractions , Equivalent weight distribution , Interfacial tension , Oleophylic groups

摘要： 通过萃取与反萃取法分离出系列石油磺酸盐的活性组分，经电喷雾质普法分析其当量分布并计算其平均当量，以气相渗透压法测得其脱磺酸基后亲油基的平均相对分子质量，并采用旋转滴法考察石油磺酸盐及其活性组分与油/水体系的界面张力。结果表明，石油磺酸盐中活性组分的组成在低及高当量区间的分布差异最大，具有宽当量活性组分分布的石油磺酸盐由于分子间结构的互补而具有适当的亲水亲油平衡，其油/水体系的界面张力能达到超低。

关键词: 石油磺酸盐 , 活性组分 , 当量分布 , 界面张力 , 亲油基