报道了新试剂５—（４—硝基苯偶氮）—８—（苯磺酰氨基）喹啉（ＮＰＢＳＱ）的合成及其与铜的显色反应。在ｐＨ＝９．２的硼砂缓冲溶液中，Ｔｗｅｅｎ８０存在下，ＮＰＢＳＱ与铜形成一种紫红色络合物，最大吸收波长为６１０ｎｍ，摩尔吸光系数＝５．１×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，铜含量在０～２０μｇ／２５ｍｌ范围内服从比尔定理，在掩蔽剂存在下，该方法己用于实际样品中铜的测定。 A new reagent 5- (4-nitrophenylazo) -8- (benzenesulfonamido) quinoline (NPBSQ) was synthesized and its color reaction with copper was reported. In the borax buffer solution with pH = 9.2, NPBSQ forms a purplish red complex with copper in the presence of Tween80 with a maximum absorption wavelength of 610 nm and a molar extinction coefficient  = 5.1 × 104 L · mol-1 · cm -1, and the content of copper is in the range of 0 ~ 20μg / 25ml, subject to Beer’s theorem. In the presence of masking agent, this method has been applied to the determination of copper in real samples.