固相萃取-电感耦合等离子体原子发射光谱法测定磷矿及磷肥中镉和铅

使用电感耦合等离子体原子发射光谱法(ICP-AES)直接测定磷矿及磷肥中Cd和Pb,受P和Ca等共存元素的干扰。当待测液中P和Ca的质量浓度分别大于Cd和Pb的10倍时,直接测定Cd、Pb结果的相对误差均大于5%,而磷矿及磷肥中P和Ca相对于Cd和Pb的含量远高于此倍数。研究表明,在pH≈2并含有0.01g/mL抗坏血酸和0.20mol/L KI试液中,强碱性阴离子交换纤维(SBAEF)能够定量萃取试液中的Cd(Ⅱ)和Pb(Ⅱ),而Ca~(2+)、PO_4~(3-)和其他共存的阳离子不被萃取;被SBAEF萃取的Cd(Ⅱ)和Pb(Ⅱ),能够通过0.07mol/L EDTA溶液定量洗脱后,使用ICP-AES测定,从而消除了P和Ca等共存组分对测定的干扰。Cd和Pb的质量浓度分别为1.00×10~(-3)~2.00μg/mL和2.00×10~(-2)~40.0μg/mL时与其发射强度呈线性,线性相关系数R2分别为0.999 294和0.999 984。方法中Cd和Pb的测定下限分别为6.00×10~(-2)和2.00×10-1μg/g。按照实验方法测定模拟样品中Cd和Pb,测定值和理论值相吻合。方法应用于实际磷矿和磷肥样品中Cd和Pb的测定,结果的相对标准偏差(RSD,n=5)不大于4.4%。分离方法也适用于火焰原子吸收光谱法(FAAS)测定磷矿和磷肥中Cd和Pb。

Determination of cadmium and lead in phosphate ore and phosphate fertilizer by solid phase extraction-inductively coupled plasma atomic emission spectrometry

The direct determination of Cd and Pb in phosphate ore and phosphate fertilizer by inductively coupled plasma atomic emission spectrometry (ICP-AES) is usually interfered by coexisting elements such as P and Ca. When the mass concentration of P and Ca in testing solution was 10 times higher than that of Cd and Pb, the relative errors of direct determination results of Cd and Pb exceeded 5%. However, the contents of Cd and Pb in phosphate ores and phosphate fertilizers were much higher than this value. It was found that the Cd (Ⅱ) and Pb(Ⅱ) in sample solution could be quantitatively extracted by strongly basic anion exchange fiber (SBAEF) in medium at pH≈2 containing 0.01 g/mL ascorbic acid and 0.20 mol/L KI. Meanwhile, Ca²⁺, PO₄^3－ and other cations were not extracted. The extracted Cd(Ⅱ) and Pb(Ⅱ) by SBAEF could be quantitatively eluted using 0.07 mol/L EDTA solution, and then determined by ICP-AES. The interference of coexisting elements such as P and Ca could be eliminated. The mass concentration of Cd and Pb in range of 1.00×10^-3-2.00 μg/mL and 2.00×10^-2-40.0 μg/mL was linear to the emission intensity. The linear correlation coefficient (R²) was 0.999 294 and 0.999 984, respectively. The low limit of determination of Cd and Pb in this method was 6.00×10^-2 μg/g and 2.00×10^-1 μg/g, respectively.The content of Cd and Pb in simulated sample was analyzed according to the experimental method. The found results were consistent with the theoretical values.The proposed method was applied to the determination of Cd and Pb in actual samples of phosphate ore and phosphate fertilizer. The relative standard deviations (RSD, n=5) were less than 4.4%. The proposed method was also applicable for the determination of Cd and Pb in phosphate ores and phosphate fertilizers by flame atomic absorption spectrometry (FAAS).