摘要
研究了一种使用超声波辅助提取（UAE）-原子荧光法测定茶叶痕量汞的快速方法。采用Plackett Burman设计从6个影响汞提取率的因素中筛选出3个显著因素一超声时间St，超声温度T和HNO3：H2O2（1：1，φ）体积A2，并采用中心组合设计和响应面法优化参数。结果表明，最优提取条件为，浸泡时间6min，St8．1min，T：70．5℃，A2：4．4mL，称样量300mg。以GBW10016茶叶为标准参考物质，与微波消解（MAD）法对比。优化条件的UAE法对GBW10016的测定值与标准值符合良好，加标回收率94．2％～102．0％，检测限0．0078μg·L^-1，重复测定的相对标准偏差小于10％。该方法应用于63个茶鲜叶样品和十种商品茶叶的测定，UAE法与MAD法结果无显著差异，汞含量（干基）在4．6～17．3μg·kg^-1之间，未超过NY659-2003限量标准。
A rapid ultrasound-assisted extraction （UAE） procedure was developed for the determination of trace mercury （Hg） in tea leaves combined with atomic fluorescence spectrometry. Three variables including sonication time （St）, ultrasonic bath temperature （T） and HNO3 ： H2O2 （1 ： 1 ,φ）volume （A2） showed the significant effect on extraction rate of total Hg evaluated by a Plackett-Burman design, and they were further optimized by a central composite design and response surface methodology. The results showed that the optimum extraction conditions were as follows： presonication time 6 min, St 8. 1 min, T 70. 5 φ,A2 4. 4 mL, and sample mass 300 mg. GBW10016 （tea leaves） was used as certified reference material; for comparative purpo- ses, a microwave-assisted digestion （MAD） was used. The result obtained by optimized UAE method showed good agreement with the certified values. Under optimal conditions, recovery was evaluated to be 94.2% - 102.0% and the limit of detection 0. 007 8 μg·kg^-1. The relative standard deviation （RSD） of replicate measurements was generally less than 10%. The proposed UAE method was successfully applied to the determination of Hg in 63 samples of fresh tea leaves and 10 different branded tea samples. No significant differences were established between the analytical results of UAE method and MAD method. The Hg concentrations of them were found in the range of 4. 6-17.3μg·kg^-1 on a dried basis, which were within the permissible limit of the NY659-2003.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2011年第10期2843-2847,共5页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(20462005)资助
关键词
超声辅助提取
响应面法
原子荧光光谱法(AFS)
痕量汞
茶叶
Ultrasound-assisted extraction
Response surface methodology
Atomic fluorescence spectrometry （AFS）
Tracemercury
Tea leaves
