双波长叠加可见吸收光谱法测定食品中的Cu  

Determination of copper in food by dual-wavelength superposition visible absorption spectrometry

作　　者：吴征真 程乙真 曾庆瑞[1] 冉纯民 江虹[1] 

机构地区：[1]长江师范学院化学化工学院,武陵山片区绿色发展协同创新中心,重庆408100

出　　处：《分析试验室》2018年第1期58-61,共4页Chinese Journal of Analysis Laboratory

基　　金：重庆市教委科技基金项目(KJ1401226)和长江师范学院科技基金项目(2016CXX088)资助

摘　　要：建立了一种测定食品中Cu的双波长叠加可见吸收光谱法。在pH 5.76的Tris-盐酸缓冲介质中,甲基蓝与Cu(Ⅱ)反应生成具有2个明显正吸收峰的蓝色离子缔合物,它们的正吸收波长分别位于527 nm和640 nm,表观摩尔吸光系数分别为2.42×10~4和2.31×10~4L/(mol·cm)。当用双波长叠加法测定时,其表观摩尔吸光系数(κ)可达4.37×10~4L/(mol·cm),它们的定量限分别为0.50 mg/100 g(527 nm),0.44 mg/100 g(640 nm)和0.24 mg/100 g(527 nm+640 nm)。Cu(Ⅱ)的质量浓度在0.1~1.6 mg/L内遵从比尔定律。还研究了吸收光谱特征、反应的适宜条件及共存物质的影响。方法用于食品中Cu的测定,加标回收率和相对标准偏差分别为97.9%~103%和2.3%~2.7%。A new fast and accurate dual-wavelength superposition visible absorption spectroscopy method for quantifying copper in food was established. In Tris-hydrochloric acid buffer of pH 5.76, methyl blue reacts with copper （ 11 ） to form a blue ion association complex with two obvious positive absorption peaks in visible area, located at 527 nm and 640 nm, respectively. Their apparent molar absorptivity （K） were 2.42 ×10^4 L/（ ool ·cm） （527 nm） and 2. 31×10^4 L/（mol ·cm） （640 nm）, respectively. When the dual-wavelength superposition absorption spectrometry was used to determine the concentrations of copper （ II ）, its apparent molar absorptivity （ k ） can be achieved 4.37×10^4 L/（ mol -cm）. Beer＇ s law was obeyed in definite mass concentration range of 0. l to 1.6 mg/L copper（ II ）. The limit of quantitation were 0.50 mg/100 g （527 nm）, 0.44 mg/100 g （640 nm） and 0. 24 mg/100 g （527 nm ＋ 640 nm）, respectively. The absorption spectral characteristic, optimum reaction conditions and effect of the coexistence material were studied. The method was applied to determine the content of copper in food with spiked recoveries and relative standard deviation （RSD） （n =6） found in the ranges of 97.9% - 103% and 2.3% -2. 7%, respectively.

关 键 词：CU 甲基蓝 双波长 吸收光谱法 

分 类 号：O657.3[理学—分析化学] TS210[理学—化学]