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铅有毒性,食品中铅的含量必须严格限制。由于铅在一定温度下具有挥发性,因此在测定样品的灰化过程中必须防止铅的挥发损失。常用的样品处理方法有干法灰化、湿法消化、高压密闭消化以及盐酸加压溶样等。分析铅时通常灰化温度低于500℃。为加快灰化速度,可加硫酸钾、硫酸或硝酸镁助灰。Thornbury认为,加助灰剂灰化处理食品样品具有安全、低试剂空白、快速和回收率好等优点。在先前的工作中,我们已经证实了在石墨炉原子吸收分析中镍对铅的基体改进作用。本文研究了用硝酸镍作助灰剂的食品灰化方法。在镍盐存在下,样品灰化温度达600℃而铅无挥发损失。硝酸镍还具有良好的助灰作用。样品灰化后用硝酸将氧化镍转化为硝酸镍,然后用平台石墨炉原子吸收法测定铅。镍的存在还提高了石墨炉灰化温度,起了基体改进作用,减少了分析中的干扰,能提高分析结果的准确度。
Lead toxicity, lead content in food must be strictly limited. Because lead is volatile at a certain temperature, lead volatilization must be prevented during ashing of the test sample. Commonly used sample processing methods are dry ash, wet digestion, high pressure airtight digestion and hydrochloric acid pressure solution. Analysis of lead is usually ashing temperature below 500 ℃. In order to speed up the ashing speed, add potassium sulfate, sulfuric acid or magnesium nitrate to help ash. Thornbury believes ash plus additive ashes are safe, have low reagent voids, are fast and have good recovery. In previous work, we have demonstrated the improved effect of nickel on the matrix of lead in graphite furnace atomic absorption spectrometry. This paper studies the use of nickel nitrate as aid ash method of food ashing. In the presence of a nickel salt, the ashing temperature of the sample reached 600 ° C and the lead had no loss of volatility. Nickel nitrate also has a good ash help role. After the sample is ashed, nickel oxide is converted into nickel nitrate by nitric acid, and then the lead is determined by the platform graphite furnace atomic absorption spectrometry. The presence of nickel also increased the ashing temperature of graphite furnace, played a matrix to improve the role of reducing the interference in the analysis, can improve the accuracy of the analysis results.