优化石墨炉原子吸收光谱法测定梨中重金属元素

Optimization of the GFAAS Determination of the Heavy qMetals in the Pear

采用石墨炉原子吸收光谱法（GFAAS）测定梨中的Cu，Cd，Pb，Mn元素。通过试验对实验参数进行了优化。在测定镉和铅时以NH4H2PO4为基体改进剂，提高了测定的灰化温度，消除了基体干扰。试验研究了灰化温度和原子化温度对吸光值的影响，试验结果表明，测定Cu，Cd，Ph，Mn元素的最佳条件为：灰化温度分别为500，300，700，900℃，原子化温度分别为2400，1600，2300，2300℃。在常压微沸下，采用HNO3—H2SO4（体积比5：1）混酸消解梨样品。在最佳测定条件下，测得梨中的Cu，Cd，Pb，Mn含量分别为（1．264±0．135），（0．441±0．008），（0．048±0．001），（3．310±0．046）mg/kg，方法的加标回收率为96．0％-103．9％，相对标准偏差RSD为1．28％～3．05％（n=8）。试验结果令人满意，测定方法简便、快速、灵敏度高。

A method for the determination of .Cu, Cd, Pb and Mn in pears by graphite furnace atomic absorption spectrometry （GFAAS） is described. The matrix modifier NH4H2PO4 can not only enhanced the ashing temperature, but also eliminate the interference of foreign ions when determining Cd and Pb. The effect of ashing temperature and atomic temperature on absorption were studied. The experimental result showed that the optimum determination conditions of Cu, Cd, Pb, Mn were found as follows： ashing temperature were 500, 300, 700, 900℃, respectively; atomic temperature were 2 400, 1 600, 2 300, 2 300 ℃, respectively. Determining the four elements at the optimal experimental condition after digestion with HNO3---H2SO4 （5 ： 1） at 90-95 ℃ and at normal pressure, the amount ofCu, Cd, Pband Mnwas （1.264±0.135） , （0.441±0.008） , （0.048± 0.001）, （3.310 ± 0.046） respectively. The recovery were between 96.0% and 103.9% and the relative standard deviations are 1.28%-3.05% （n=8） . The results are satisfactory and a rapid, simple and reliable method with high sensitivity was established.