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

邢夏; 徐进力; 陈海杰; 邢辰; 白金峰; 张勤

doi:10.15898/j.cnki.11-2131/td.2015.03.010

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

中国地质科学院地球物理地球化学勘查研究所, 河北廊坊 065000

基金项目: 中国地质调查局地质矿产调查评价项目(1212011120277)

详细信息

作者简介: 邢夏, 工程师, 主要从事地球化学样品的分析测试工作.E-mail: 13833667427@139.com

通讯作者: 徐进力, 工程师, 主要从事地球化学样品的分析测试工作.E-mail: 80368070@qq.com

中图分类号: O657.31;O614.123

收稿日期: 2013-12-22

修回日期: 2015-05-08

录用日期: 2015-05-13

刊出日期: 2015-03-25

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

Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang 065000, China

More Information

Corresponding author: XU Jin-li, 80368070@qq.com

Received Date: 22 December 2013

Revised Date: 08 May 2015

Accepted Date: 13 May 2015

Publish Date: 25 March 2015

摘要

摘要:
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(0.29 ng/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。
- 金矿区植物样品 /
- 痕量金 /
- 石墨炉原子吸收光谱法 /
- 抗坏血酸 /
- 瓷坩埚
Abstract:
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 of 1000℃ and 2000℃, respectively, and ascorbic acid is used as the matrix modifier. Sample ashing temperature of 500℃ 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.
- plant samples in gold mining area /
- trace gold /
- Graphite Furnace Atomic Absorption Spectrometry /
- ascorbic acid /
- porcelain crucible

HTML全文

图 1 基体改进剂对灰化和原子化温度的影响

Figure 1.

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图 2 不同灰化温度下植物样中金的分析结果

Figure 2.

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表 1 仪器工作条件和石墨炉升温程序

Table 1. Working parameters of instrument and temperature program of graphite furnace

GFAAS仪器工作条件		石墨炉升温程序
工作参数	设定条件	步骤	温度 (℃)	斜坡 (℃/s)	保持时间 (s)
波长	242.8 nm	干燥	90	10	5
狭缝	1.2 nm		100	10	5
灯电流	8.0 mA		110	10	5
积分方式背景扣除方式	峰高 Zeeman	灰化	1000	150	10
进样体积	15.0 μL	原子化	2000	0	3
基体改进剂体积	5.0 μL	除残	2300	0	3
辅助气流速	0.2 L/min
积分时间	1.5 s

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表 2 方法精密度和加标回收率实验

Table 2. Precision and spiked recovery tests of the method

植物样品	精密度				加标回收率
植物样品	6次分次测定值 (ng/g)	平均值 (ng/g)	标准偏差 (ng/g)	RSD (%)	样品含量 (ng/g)	加标量 (ng/g)	测量值 (ng/g)	回收率 (%)
玉米茎叶	59.151.857.6 50.157.358.4	55.7	3.78	6.8	3.33	5.00	7.80	88.9
蒿草	4.594.954.18 4.415.135.26	4.75	0.43	8.9	4.23	5.00	9.50	104.7
羊不吃叶	3.563.023.98 3.964.054.29	3.81	0.45	11.9	52.7	50.0	94.6	83.8

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