以月桂基硫酸钠溶液为滴定剂,以溴酚蓝溶液为指示剂,在十六烷基三甲基溴化铵阴离子表面活性剂存在下同步返滴定法测定石油磺酸钠活性物的含量.根据同步返滴定法的原理,提出了活性物含量的计算公式.用两件标准样品(其中1#含活性物45.30%,2#含活性物8.49%),以不同质量比例混合配成5份含不同已知量活性物的试样,按所提出的方法测定,根据测定值与已知计算值的偏差判断方法的准确度,结果表明:算得的相对误差均小于±2.0%,并用上述两标准样品连续分析10次,试验方法的精密度,计算得1#和2#样品的相对标准偏差(n=10)分别为0.9%,2.0%.

The content of active substance in sodium petroleum sulfonate was determined by synchronous back-titration in the presence of the anionic surfactant,CTMAB. Using sodium lauryl sulfate solution as titrant and bromophenol blue as indicator. Based on the principle of synchronous back-titration,the formula for calculation of active substance content was proposed. The accuracy of the proposed method was tested by analyzing 5 samples with known active substance contents prepared by mixing 2 samples of sodium petroleum sulfonate (with known active substance contents of 45.30% in sample 1# and 8.49% in sample 2#) in different ratios. Relative errors between the determined values and the calculated known values were found to be less than ±2.0%. Precision was tested on the 2 standard samples mentioned above,values of RSD′s (n=10) found were 0.9% for sample 1# and 2.0% for sample 2#.