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高温燃烧水解-离子色谱法测定植物样品中的氟

Quantification of Fluorine in Plants by High Temperature Combustion Hydrolysis-Ion Chromatography

  • 摘要: 建立了高温燃烧水解-离子色谱测定植物样品中不同含量范围氟的分析方法,色谱条件为Dionex IonPac AS18分离柱(4 mm×250 mm),Dionex IonPac AG18保护柱(4 mm×50 mm),ASRS ULTRAⅡ自动再生微膜抑制器,电导检测器。采用纯水作为吸收介质,使样品溶液与标准溶液基体一致,过滤后可直接测定。样品溶液中常见的Cl-、NO3-、SO42-、PO43-、CO32-、HCO3-等阴离子不干扰F-的测定。为消除样品热解过程中产生的乙酸干扰,对氟含量较高(xx~xxx μg/g)的样品,采用20 mmol/L的NaOH淋洗液等度淋洗,进样体积为25 μL;对氟含量较低的样品(0.x~x μg/g),进样体积为100 μL。方法具有较宽的线性范围和较好的稳定性,检出限为0.5 mg/kg,适用于痕量分析;应用于灌木枝叶和茶叶等4个氟含量较高(xx~xxx μg/g)的植物标准物质的测定,相对标准偏差(RSD)<6%(n=6);应用于低氟的小麦粉和大米粉样品测定,加标回收率为90%~110%,可以满足不同氟含量植物样品中氟测定的需要,具有自动化程度高、操作简单、对环境友好等特点。

     

    Abstract: A new method for the determination of fluorine in plants was developed by high temperature combustion hydrolysis-Ion Chromatography. Chromatographic conditions were selected as Dionex IonPac AS18 separation column (4 mm×250 mm), Dionex IonPac AG18 protect column (4 mm×50 mm), ASRS ULTRA Ⅱ suppressor (4 mm) and conductivity detection. The fluorine ion was absorbed by pure water, which provided the same matrix between the sample solution and the standard solution. The sample solution was analyzed directly by Ion Chromatography with a simple procedure and low cost after filtration. The anions such as Cl-, NO3-, SO42-, PO43-, CO32-, HCO3- have no interferences with F-, except the acetic acid produced in the process of pyrolysis. In order to eliminate the interference from acetic acid, 20 mmol/L NaOH solution was used as equal eluent for higher fluorine sample (xx-xxx μg/g) with the 25 μL sample volume, while for lower fluorine sample (0.x-x μg/g)with the 100 μL sample volume. The new method has wide linear range, high stability and a low detection limit as of 0.5 mg/kg. Four plant reference materials of shrub and tea with higher fluorine contents (xx-xxx μg/g) were studied as the relative error is lower than 10% and the relative standard deviation is lower than 6%. For wheat and rice samples which have lower fluorine content, the recovery by standard addition is 90%-110%. Compared with ion selective electrode and spectrophotometry, Ion Chromatography can be used for samples with a larger range of fluorine concentration, and has the advantages of high automation, easy operation and is environmentally friendly.

     

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