树脂相分光光度法测定杂粮中微量铁

RESIN-PHASE SPECTROMETRY ANALYSIS FOR TRACE IRON IN CEREALS

在p H值为5左右的HAc-NH4Ac缓冲溶液中铁(Ⅱ)与2,2’—联吡啶生成有色络阳离子,与强酸性阳离子交换树脂进行交换吸附,即可进行树脂相分光光度法测定微量Fe(Ⅱ)。最大吸收波长λmax=522 nm,表观摩尔吸光系数为9.8×104L·mol-1·cm-1,比水相分光光度法测定Fe(Ⅱ)的摩尔吸光系数高出近12倍。铁(Ⅱ)的含量在0.2~20mg·L-1范围内服从Beer定律。测定了黑豆、红豆、荞麦和莜麦样品中的微量铁,相对标准偏差为1.9%~3.5%,回收率在97.8%~103%之间,结果满意。

Fe( II) and 2,2'- bipyridine coordinated a colored complex cation in HAc- NH4 Ac buffer solution of p H = 5. 0 and this colored complex cation was adsorpted by the strong acidic cation changeable resin,hence,the trace Fe( II) can be determined by the resin phase spectrometry with the maximum wavelength at 522 nm,and the apparent molar absorbance is 9. 8 × 104 L · mol- 1·cm- 1,which is twelve times sensitive than that of direct water phase spectrometry. The Beer's law was obeyed when Fe( II) was in the range of 0. 2 ~ 20 mg·L- 1. The result was applied to determine the trace iron in small red beans,black soy beans,buckwheat and oat noodle samples with relatively higher sensitivity and precision. The relative standard deviations and recoveries of which are1. 9% ~ 3. 5% and 97. 8% ~ 103% respectively.