Barin Juliano S, Bartz Fabiane R, Dressier Valderi L, Paniz José N G, Flores Erico M M
Departamento de Química, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil.
Anal Chem. 2008 Dec 1;80(23):9369-74. doi: 10.1021/ac8015714.
A procedure based on microwave-induced combustion coupled to flame furnace (FF) atomic absorption spectrometry (FF-AAS) was used for analysis of solid samples. Botanical samples were prepared as pellets and introduced into a quartz holder device. This device was fitted to a glass chamber that was used for the combustion step. The complete device was coupled to the flame furnace by using poly(tetrafluoroethylene) and quartz tubes. The glass chamber was placed inside a microwave oven in a position previously set to receive the higher power of microwave radiation. Ignition was performed by microwave radiation using a small piece of paper wetted with NH4NO3 solution. An oxygen flow was used to assist the sample combustion and also to transport the combustion products up to the heated FF positioned above an air/ acetylene burner. Flame furnace temperature, oxygen flow rate, flame stoichiometry, and sample mass range were evaluated. Cadmium and lead were determined in botanical samples as examples to demonstrate the potential of the proposed procedure for trace analysis. Sample masses up to 60 mg could be used, allowing a limit of detection as low as 0.003 and 0.24 microg g(-1) for Cd and Pb, respectively. Integrated absorbance was used with an integration time of 30 s. Background signals were always low, and relative standard deviation (n = 5) was below 9% for Cd and 11% for Pb. The throughput was 20 determinations/h, including the weighing step. Accuracy was between 94 and 105%, and calibration was performed using standard solutions. The combustion device could be easily adapted to conventional atomic absorption spectrometers.
一种基于微波诱导燃烧与火焰炉（FF）原子吸收光谱法（FF-AAS）联用的方法用于固体样品分析。植物样品制成颗粒后引入石英样品架装置。该装置安装在用于燃烧步骤的玻璃腔室中。整个装置通过聚四氟乙烯管和石英管与火焰炉相连。玻璃腔室放置在微波炉内，位置预先设定为接收较高功率的微波辐射。使用一小片用硝酸铵溶液浸湿的纸通过微波辐射进行点火。使用氧气流辅助样品燃烧，并将燃烧产物输送到位于空气/乙炔燃烧器上方的加热火焰炉中。对火焰炉温度、氧气流速、火焰化学计量比和样品质量范围进行了评估。以植物样品中镉和铅的测定为例，证明了所提出方法在痕量分析中的潜力。可使用高达60 mg的样品质量，镉和铅的检测限分别低至0.003和0.24 μg g-1。积分吸光度用于30 s的积分时间。背景信号始终较低，镉的相对标准偏差（n = 5）低于9%，铅的相对标准偏差低于11%。分析通量为每小时20次测定，包括称重步骤。准确度在94%至105%之间，使用标准溶液进行校准。该燃烧装置可轻松适配于传统原子吸收光谱仪。
