二溴苯基荧光酮在表面活性剂的存在下,已用于许多金属离子的光度分析。本文研究了在CTMAB存在下,试剂与镁的显色反应,在pH 10.5条件下,灵敏度较高,其摩尔吸光系数e为1.1×10~5,在柠檬酸钠存在下,可掩蔽200μg Ca~(2+),故可应用于水中镁的测定。手续简便,结果较为满意。一仪器与试剂三乙醇胺溶液:1+3;柠檬酸钠溶液:5% CTMAB:0.2%;二溴苯基荧光酮溶液:0.02% 721型分光光度计二试验方法吸取2.5μg镁标准溶液于25ml量瓶中,加入柠檬酸钠溶液5ml,三乙醇胺溶液4ml,加二溴苯基荧光酮溶液2ml,加CTMAB 0.7ml,加水稀至刻度,摇 Dibromophenylfluorone has been used for the photometric analysis of many metal ions in the presence of surfactants. In this paper, the color reaction of reagent with magnesium was studied in the presence of CTMAB. Under the condition of pH 10.5, the sensitivity was high. The molar extinction coefficient e was 1.1 × 10 ~ 5. In the presence of sodium citrate, (2+), it can be applied to the determination of magnesium in water. Procedures are simple, the result is more satisfied. An instrument and reagents triethanolamine solution: 1 +3; sodium citrate solution: 5% CTMAB: 0.2%; dibromophenylfluorone solution: 0.02% 721 spectrophotometer two test methods Pipette 2.5μg magnesium standard solution in 25ml Volumetric flask, add sodium citrate solution 5ml, triethanolamine solution 4ml, add dibromophenylfluorone solution 2ml, add CTMAB 0.7ml, add water dilute to the mark, shake