Abstract: The noncomplete digestion method was applied to the treatment of lubricating oil sample，i．e．the sample was digested in concentrated nitric acid， and then the product of the digested sample was dissolved in emulsifier Triton X -100 obtaining the homogeneous and transparent solution of the sample.Thus the noncomplete digestion-spectrophotometer method for determination of calcium in lubricating oil was established． The interference ions are masked by EDTA. Experimental conditions are carefully selected. The results show that in the presence of 5-Br-PADAP, emulsifier TritonX-100 and KH₂PO₄-NaOH, Ca reacts with 5-Br-PADAP to form a complex with maximum absorption wavelength at 555 nm. Under the optimum conditions Beers law is obeyed in the range of 0～20.0 μg/mL of Ca with the correlative coefficient of 0.999 6 and an apparent molar absorptive coefficient of 3.84×10⁴ L/(moL·cm). The average recovery for Ca is 98.03%(n=6) from model samples and 97.4 %～102. 9% in real lubricating oil case with precision of 2.62%～3.13% RSD.

Key words: Calcium  , Non-ionic surfactant , Noncomplete digestion methods ,  , spectrophotometry

摘要： 非完全消化法处理润滑油样品,即先用浓硝酸消解样品,再用乳化剂TritonX-100溶解消解产物而
配制成均匀透明的样品溶液,建立非完全消化-分光光度法测定润滑油中钙的方法。通过加入联合掩蔽剂掩蔽干
扰离子,结果表明,在5-Br-PADAP、TritonX-100、KH₂PO ₄-NaOH 缓冲溶液存在下,钙和显色剂形成的配合
物最大波长为555nm,在最佳条件下,钙的线性范围为0~20.0μg/mL,相关系数r=0.9996,摩尔吸光系数ε =
3.84×104 L/(moL·cm),人工合成样品的平均回收率为98.03%(n=6)。对实际润滑油样品分析,相对标准偏差为
2.62%~3.13%,加标回收率为97.4%~102.9%。

关键词: 钙 ,  ,  , 非离子表面活性剂 ,  , 非完全消化法 , 分光光度法