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采用硝酸-盐酸混合酸溶解,5 %(V/V)盐酸作为稀释酸,试液使用超声振荡混匀,基体匹配法绘制校准曲线消除基体效应的影响,建立了使用多向观测-电感耦合等离子体原子发射光谱法(ICP-AES)同时测定湿法磷酸中铝、镁、铁、钾、钠、锰、钙和铬的分析方法.根据分析线的选择原则,结合待测元素的检测范围,选择无干扰或干扰小、峰形对称、灵敏度高的谱线作为分析线.通过径向观测方式,减小样品稀释倍数,降低电离干扰,测定含量较高的铝、镁、铁;通过轴向观测方式,提高灵敏度,测定含量较低的锰、钙、铬;通过轴向衰减观测方式,减小谱线强度,测定含量较低的钾和钠.被测元素在一定质量浓度范围内与其发射强度呈线性,校准曲线的线性相关系数为0.998 6~0.999 9.方法的检出限为0.001 5~0.009 1 μg/mL.按照实验方法测定两个湿法磷酸样品中的铝、镁、铁、钾、钠、锰、钙和铬,结果的相对标准偏差(RSD,n=12)为2.1%~8.1%.选择两个湿法磷酸样品,分别采用基体匹配法和标准加入法并使用ICP-AES测定,再采用其他化学方法进行比对(其中,铁采用邻菲哆啉比色法测定,铝采用不预分离干扰的氟盐取代-EDTA滴定法测定,钙采用高锰酸钾滴定法测定,锰采用过硫酸铵-亚铁滴定法测定,钾、钠、铬和镁均采用火焰原子吸收光谱法测定),所得铝、镁、铁、钾、钠、锰、钙和铬的测定结果基本吻合.

The sample was dissolved with mixed acid composed by nitric acid and hydrochloric acid.5%(V/V) hydrochloric acid was used as diluted acid.The sample solution was uniformly mixed by ultrasonic oscillation.The influence of matrix effect was eliminated by preparing the calibration curve with matrix matching method.Thus, a determination method of aluminum, magnesium, iron, potassium, sodium, calcium, manganese and chromium in wet-process phosphoric acid by multi-directional observation-inductively coupled plasma atomic emission spectrometry (ICP-AES) was established.According to the selection principle of analytical lines as well as the detection range of testing elements, the spectral lines with no or low interference, symmetrical peak shape and high sensitivity were selected as the analytical lines.Aluminum, magnesium and iron with high content were determined by radial observation mode to reduce the sample dilution ratio and ionization interference.Manganese, calcium and chromium with relatively low content were determined by axial observation mode to improve the sensitivity.Potassium and sodium with relatively low content were determined by axial attenuation observation mode to reduce the spectral intensity.The mass concentration of test elements in certain range were linear to their corresponding emission intensity.The linear correlation coefficients of calibration curves were between 0.998 6 and 0.999 9.The detection limits of method were between 0.001 5 μg/mL and 0.009 1 μg/mL.The content of aluminum, magnesium, iron, potassium, sodium, calcium, manganese and chromium in two wet-process phosphoric acid samples was determined according to the experimental method.The relative standard deviations (RSD, n=12) of results were between 2.1% and 8.1%.Two wet-process phosphoric acid samples were determined by matrix matching method and standard addition method combined with ICP-AES respectively, and then compared with other chemical methods (wherein, iron was determined by phenanthroline colorimetry;aluminum was determined by fluoride replacement-EDTA titration without pre-separation;calcium was determined by potassium permanganate titration method;manganese was determined by ammonium persulfate-ferrous titration;potassium, sodium, chromium and magnesium were determined by flame atomic absorption spectrometry).The determination results of aluminum, magnesium, iron, potassium, sodium, calcium, manganese and chromium showed good agreement.