5,10,15,20-四(4-甲氧基-3-磺酸苯基)卟啉光度法测定食品中痕量锰的研究

Study on 5,10,15,20-tetrakis(4-methoxyl-3-sulphophenyl)porphine for the spectrophotometric determination of trace manganese in foods

在 Cd(Ⅱ)和羟胺存在下,于 pH 9.2时,锰很快和5,10,15,20-四(4-甲氧基-3-磺酸苯基)卟啉形成1:1的配合物。工作曲线回归方程为4=0.00353+0.0743x,相关系数 r=0.9993,其最大吸收波长在469nm 处,摩尔吸光系数为1.07×10~5。若以半胱氨酸作掩蔽剂,可成功地用于茶液、黄酒、大米和黄豆等食品中痕量锰的测定,所得结果与 AAS 的很一致。

The complexing reaction of 5,10,15,20-tetrakis(4-methoxyl-3-sulphophenyl)porphine[T(4-MOP)PS_4]with manganese(Ⅱ)in the pre-sence of hydroxylamine and cadmium(Ⅱ)as au-xiliary complexing agents has been studied.Thereagent is found to be highly sensitive for thedirect determination of trace manganese(Ⅱ).Atroom temperature and pH 9.2,the complex ofmanganese(Ⅱ)with T(4-MOP)PS_4(1:1)is formedrapidly;it is stable for 6 hours;the apparentmolar absorptivity is 1.07×10~5 L·mol^(-1)·cm^(-1).The interference of foreign ions is examined inthe presence and absenco of the masking agentL-cysteine.The method has successfully beenapplied to the direct determination of trace manga-nese in foods.The result obtained is very similarto that of atomic absorption spectrophotometricanalysis.Beer's law is obeyed in the range of0～10.0 μg Mn(Ⅱ)/25mL.