为实现油田水集输管道的缓蚀效果，保证其在最佳含量下起到缓蚀作用，有效检测缓蚀剂（咪唑啉类缓蚀剂）在地层水中的残余量，对现场缓蚀剂加注工艺的指导具有重要意义。应用紫外分光光度法测定地层水中咪唑啉类缓蚀剂时遇到了严重的背景干扰问题。为解决此阻扰，试验采用在选择扫描步长为5 nm的条件下对原始紫外光谱求取二阶导数的方法。结果表明，此方法可有效消除地层水中所含其他物质对缓蚀剂在波长240 nm处检测时的干扰，测得咪唑啉缓蚀剂的质量浓度在10~100 mg·L^-1内与相应的紫外光谱的二阶导数呈线性关系，其检出限（3s）为0.07 mg·L^-1。按标准加入法测得方法的回收率为99.7%~102%，测定值的相对标准偏差（n=6）为0.83%~6.3%。分析样品时，可根据缓蚀剂的加入量从传输管线中移取水样1 L，经离心和滤纸过滤后，取滤液按仪器工作条件进行紫外分光光度测定。

It was of great significance to have an effective method for the field analysis of water sample from formation water of oil field for its residual amount of imidazoline corrosion inhibitor (IMCI), in order to control the optimum amount of IMCI to be added to the piping system and to attain at a high efficiency in the anticorrosion of the piping system. UV spectrophotometry was tested for use in this case, but serious interference from the co-existing impurities in the water sample was encountered making the determination impossible. To overcome this obstacle, a scanning stepping of 5 nm was chosen, and then its 2nd-derivate was derived. It was shown that the interference mentioned above was effectively eliminated by this method, and the absorbance of IMCI was detected at the wavelength of 240 nm. Linear relationship between values of 2nd-derivates and the mass concentrations of IMCI was found in the range from 10 to 100 mg·L^-1. Detection limit (3s) found was 0.07 mg·L^-1. Test for recovery was made by standard addition method, giving results in the range of 99.7% to 102%. Values of RSDs (n=6) found were in the range from 0.83% to 6.3%. In the analysis of unknown sample, 1 L of the water sample was taken from the piping according to the amount of IMCI added, and it was centrifuged and filtered through filtering paper, and the filtrate was analyzed by derivative UV spectrophotometry under the working condition of the instrument.