低场核磁共振检测食品中总无机硫

Detecting total inorganic sulfur in food by low-field nuclear magnetic resonance

在食品、药材的生产加工过程中,经常加入不同价态的含硫化合物进行漂白、防腐和抗氧化。过量使用这些物质会对人体产生损害。因此,应加强对这些物质的检测。本文中,笔者报道了一种基于低场核磁共振技术的检测食品中总无机硫含量的新方法。提出了一种简单的前处理方法,利用过氧化氢(H2O2)将食品样品中所有无机硫氧化至最高价态(硫酸根)。制备了一种含钡盐的水凝胶作为检测试剂。利用Ba^2+和SO4^2-之间的相互作用改变水凝胶中的化学环境,带来质子弛豫时间的改变。在模拟实验中,应用低场核磁共振分析仪测量了凝胶体系在不同浓度Na2 SO4溶液中的横向弛豫时间T2,初步得到了T2与SO4^2-浓度之间的关系曲线。本研究提出的方法成本低、耗时短、前处理简单,有望用于食品中无机硫的快速检测。

In the production process,sulfide are offen used to bleaching,antisepsis and antioxidation,although the overuse of these compounds is harmful to people s health.Thus,detecting of these compounds is very important.Here,we report a new method based on low-field nuclear magnetic resonance(LF-NMR)technology to detect the total inorganic sulfur content.By using H2O2 as oxidizing agent,all kinds of sulfur were oxidized to highest valence state(sulfate ion).A hydrogel containing barium ions was synthesized as detection reagent.The interaction between barium ion and sulfate ion may change the motivation of water molecules in the system,leading to corresponding change of the relaxation time of the protons in the system.As simulation experiments,LF-NMR was performed to measure the transverse relaxation time(T2)of the hydrogels soaking in Na2SO4 aqueous solution with different concentration.The relationship between T2 and Na2SO4 concentration was obtained.Thus,this study provides a novel method for detection of the inorganic sulphur in food,which is low costed,rapid,high-throughput with easy pretreatment.