多溴代苯基荧光酮光度法测定纯锌中痕量铅

Photometric Determination of Trace Amount of Lead in Pure Zinc with Polybromo-Phenylfluorone

研究了多溴代苯基荧光酮显色剂3′,5′-二溴-4′-羟基-4,5-二溴苯基荧光酮(DBHDB-PF)与铅(Ⅱ)的显色反应,结果表明:在十六烷基三甲基溴化铵微乳液存在下及pH 10.0的硼砂-氢氧化钠缓冲溶液中,显色剂DBHDBPF与铅形成2比1的稳定络合物。其最大吸收波长位于波长592nm处,表观摩尔吸光率为1.58×105L.mol-1.cm-1。据此提出了甲基异丁基酮萃取分离、DBHDBPF光度法测定纯锌中铅含量的方法。铅的质量浓度在1.8mg.L-1以内符合比耳定律,方法的检出限(3S/N)为0.12mg.L-1。应用此方法测定了GBW 02701和GBW 02702纯锌标准物质中微量铅的含量,测定结果与认定值相一致。

The color reaction between a polybromo-phenylfluorone chromagenic reagent, 3＇, 5＇-dibromo-4＇- hydroxy-4,5-dibromophenylfluorone （DBHDBPF）, and Pb （ Ⅱ ） was studied. In a Na2 B4 O7-NaOH buffer solution of pH 10. 0, and in the CTMAB microemulsion, a stable coordination complex with the molar ratio （DBHDBPF ： Pb） of 2 to 1, was formed, with its absorption maximum at the wavelength of 592 nm.Value of apparent molar absorptivity was found to be 1.58×10^5L·mol^-1·cm^-1. Based on these facts, a method of spectrophotometry for the determination of lead in pure zinc was proposed using 4-methyl-2-pentanone （MIBK） to extract Pb（ Ⅱ ） from sample solution. Beer＇s law was held in the range within 1.8 mg · L^-1 , with detection limit （3S/N） of 0. 12 mg · L^-1. The proposed method was applied to the determination of Pb in CRM＇s of pure zinc （GBW 02701 and GBW 02702）, giving results in consistency with the certified values.