石墨炉原子吸收光谱法测定铁矿石中痕量铅

消除基体干扰是石墨炉原子吸收光谱法测定铁矿石试样中痕量铅的一个难题。实验通过将铅标准溶液系列加入到铁矿石标准样品溶液中以绘制标准加入校准曲线,然后再用建立的标准加入校准曲线对其他铁矿石试样中铅进行测定以消除铁矿石的基体干扰。据此,建立了标准加入校准法-石墨炉原子吸收光谱法(GFAAS)测定铁矿石试样中痕量铅的方法。实验表明,设置灰化程序为350 ℃保持30 s,600 ℃保持15 s,原子化温度为1 600 ℃、保持4 s,标准加入校准曲线的相关系数为0.999 8,方法的检出限为0.43 mg/kg。方法应用于铁矿石标准样品中铅的测定,测定值和认定值吻合性较好,相对标准偏差(RSD,n=6)小于7.0%。采用方法对铁矿石标准样品和实际样品进行加标回收试验,回收率在93%～98%之间。

Determination of trace lead in iron ore by graphite furnace atomic absorption spectrometry

The elimination of matrix interference was a difficulty in determination of trace lead in iron ore by graphite furnace atomic absorption spectrometry (GFAAS). The standard solution series of lead were added into certified reference material solution of iron ore to prepare standard addition calibration curve. Then, the established standard addition calibration curve was used for determination of lead in other iron ore samples to eliminate the matrix interference. On the basis of this, a determination method of trace lead in iron ore sample was established by GFAAS combined with standard addition calibration method. The experimental conditions were optimized as follows: the ashing program was 35 ℃ keeping for 30 s and 600 ℃ keeping for 12 s; the atomization temperature was 1 600 ℃and kept for 4 s. The results showed that the correlation coefficient of standard addition calibration curve was 0.999 8. The detection limit of method was 0.43 mg/kg. The proposed method was applied to the determination of lead in certified reference material of iron ore. The results were consistent with the certified values. The relative standard deviation (RSD, n=6) was less than 7.0%. The recovery tests of certified reference material and actual sample of iron ore were conducted according to the experimental method. The recoveries were between 93% and 98%.