中文摘要：

根据烷基型甜菜碱两性表面活性剂在等电点以下pH值、呈阳离子表面活性剂的特性，采用金橙Ⅱ法对八烷基二甲基甜菜碱（BS-8）、十二烷基二甲基甜菜碱（BS-12）和十八烷基二甲基甜菜碱（BS-18）同系物测定的方法进行了研究。结果表明，测定BS-8和BS-12最适pH值范围是小于3．6，BS-18小于2．0，BS-18测定的显色剂金橙Ⅱ的体积大于BS-8和BS—12测定所用金橙Ⅱ的体积，BS—18采用乙酸乙酯萃取具有好的测定结果，不同于BS—12和BS-8采用氯仿作为萃取剂。BS-8和BS-12测定的线性范围是0．10～40．00μg·mL^-1，BS-18的线性范围1．00～50．00μg·mL^-1；BS-8、BS-12和BS-18的回收率分别为100．4％～101．2％、99．31％-102．0％和96．25％-105．0％。土壤中常见的阳离子和阴离子在一定的浓度范围内对该测定方法没有干扰。

英文摘要：

Based on the characteristics of amphoteric surfanctants, alkyl betaine, which have positive charge when the solution pH is smaller than their isoelectric points, the determination method for alkyl betaine homologous compounds, i.e. Octyl-Betaine （BS-8）, Dodecane-Betaine （BS-12）, Octadecane-Betaine （BS-18）in soil solution using the Gold Orange Ⅱ Method were studied in this paper. The results showed that the optimum pH for BS-8 and BS-12 determination is below 3.6, and for BS-18 is below 2.0. The volume of gold orange Ⅱ used in determination of BS-18（6.5 mL）is more than that of both BS-8 or BS-12（3.0 mL）. Chloroform is the extractant of both BS-12 and BS-8, but ethyl acetate as extractant have a better effect for BS-18. The detection limits of BS-8, BS-12 and BS-18 are 0.01μg.mL^-1, 0.05 μg.mL^-1 and 0.1 μg. mL^-1 respectively, and the linear ranges of standard curves between absorbance and the concentration of BS-8, BS-12 and BS-18 are 0.10-40.00 μg. mL^-1 （R2= 0.998 7）, 0.10-40.00 μg. mL^-1（R2= 0.998 9 ）, 1.00-50.00μg. mL^-1 （R2=0.999 0）, respectively. The recovery ratios of BS-8, BS-12 and BS-18 are 100.4%-101.2%,99.31%-102.0% and 96.25%-105.0% respectively. The common cations and anions in the soil solution in a certain range have no effect on the accuracy of this method.