电感耦合等离子体原子发射光谱法测定硫酸锰中钙镁

Determination of calcium and magnesium in manganese sulfate by inductively coupled plasma atomic emission spectrometry

在酸性和低温条件下,直接用水溶解试样,在选定的测量条件下,用电感耦合等离子体原子发射光谱法（ICP-AES）测定了硫酸锰中钙和镁含量.根据谱线的谱图、背景轮廓和强度值,选择了信背比高、不受或少受光谱干扰、检出限低的Ca 317.9 nm、Mg 285.2 nm谱线分别作为钙、镁的分析谱线,消除了基体元素锰对钙和镁测定的干扰影响.钙和镁校准曲线的线性相关系数分别为0.999 7和0.999 5,检出限分别为0.007 μg/mL和0.002 μg/mL,定量下限分别为0.022 μg/mL和0.007 1 μg/mL.对同一样品独立测定8次,得到相对标准偏差（RSD）为0.78％（钙）和0.93％（镁）;方法的加标回收率在97％～101％之间.样品的测定值与滴定法的测定值基本一致,但实验方法操作相对简单、灵敏度和精密度较好,适合硫酸锰申钙和镁含量的测定.

Under acidic,low-temperature conditions,the sample was dissolved directly in water,and under the selected measurement conditions,calcium and magnesium contents in manganese sulfate were determined by inductively coupled plasma atomic emission spectrometry （ICP-AES）.According to the spectra,the background profile and the intensity values,the experiment selected spectral lines Ca 317.9 nm and Mg 285.2 nm as the analytical lines for calcium and manganese for the high signalto-background ratio,were not or less affected by spectral interference and showed low detection limits so that the interference of matrix element manganese with the determination of calcium and magnesium was eliminated.The linear correlation coefficients of the calibration curves for calcium and magnesium were 0.999 7 and 0.999 5,respectively,the detection limits were 0.007 μg/mL and 0.002 μg/mL,and the lower limits of quantification were 0.022 μg/mL and 0.007 1 μg/mL,respectively.The same sample was determined independently eight times to obtain the relative standard deviations （RSD） as 0.78％ （Ca） and 0.93％ （Mg）.The standard recovery of the method was between 97％ and 101％.The measured values of the sample were consistent with those obtained by titration method,but the proposed method is relatively simple to operate,exhibits good sensitivity and precision and thus is suitable for the determination of calcium and magnesium contents in manganese sulfate.