抗坏血酸为基体改进剂石墨炉原子吸收光谱法测定金矿区植物样品中的痕量金

Determination of Trace Gold in Plant Samples from a Gold Mining Area by Graphite Furnace Atomic Absorption Spectrometry with Ascorbic Acid as the Matrix Modifier

应用石墨炉原子吸收光谱法（GFAAS）测定地球化学样品中的低含量金具有较高的准确度,但用于测定植物样品中痕量金时,传统方法的称样量较大（20 g）,样品在马弗炉中灰化不完全,检出限较高（0.29ng/g）。本文确定了应用GFAAS分析金矿区植物样品中痕量金的测定条件,石墨炉的升温程序为：金的灰化温度1000℃,原子化温度2000℃,以抗坏血酸为基体改进剂,瓷坩埚为灰化器皿,且将样品的灰化温度降低到500℃,灰化时间2.0 h,确保了样品灰化完全且待测元素不发生挥发损失。本方法称样量较小（5.0 g）,检出限为0.03 ng/g,精密度为6.8%~11.9%,加标回收率为83.8%~104.7%。经过金矿区实际植物样品试验,发现不同植物对金的富集能力相差较大,其中玉米植株对金的富集能力强。

Determination of low-level gold in geochemical samples by Graphite Furnace Atomic Absorption Spectrometry（ GFAAS） has good accuracy. However,this method is limited to the determination of trace gold in plants due to the large sample amount of 〉20 g required,incomplete ashing in the muffle furnace,and a high detection limit of 0. 29 ng / g. A revised method of determining trace gold in plant samples from a gold mining area by GFAAS is proposed. The heating process in a graphite furnace Involves ashing and atomization temperatures of1000℃ and 2000℃,respectively,and ascorbic acid is used as the matrix modifier. Sample ashing temperature of500℃ and an ashing time of 2. 0 h in a porcelain crucible can guarantee the complete ashing of samples and avoid volatilization loss. This method uses small weight samples of 5. 0g,the detection limit is 0. 03 ng / g,the precision is 6. 8%- 11. 9%,and standard addition recoveries are 83. 8%- 104. 7%. It was also found that different plants have different capacities of gold enrichment with maize containing the highest enrichment.