Silva M M, Goreti M, Vale R, Caramão E B
Instituto de Quimica, Universidade Federal do Rio Grande do Sul, P.O. Box 15003, Av. Bento Goncalves, 9500 CEP 91501-970, Porto Alegre, RS, Brazil.
Talanta. 1999 Dec 6;50(5):1035-43. doi: 10.1016/s0039-9140(99)00216-7.
A procedure for lead, cadmium and copper determination in coal samples based on slurry sampling using an atomic absorption spectrometer equipped with a transversely heated graphite tube atomizer is proposed. The slurries were prepared by weighing the samples directly into autosampler cups (5-30 mg) and adding a 1.5 ml aliquot of a diluent mixture of 5% v/v HNO(3), 0.05% Triton X-100 and 10% ethanol. The slurry was homogenized by manual stirring before measurement. Slurry homogenization using ultrasonic agitation was also investigated for comparison. The effect of particle size and the use of different diluent compositions on the slurry preparation were investigated. The temperature programmes were optimized on the basis of pyrolysis and atomization curves. Absorbance characteristics with and without the addition of a palladium-magnesium modifier were compared. The use of 0.05% m/v Pd and 0.03% m/v Mg was found satisfactory for stabilizing Cd and Pb. The calibration was performed with aqueous standards. In addition, a conventional acid digestion procedure was applied to verify the efficiency of the slurry sampling. Better recoveries of the analytes were obtained when the particle size was reduced to <37 mum. Several certified coal reference materials (BCR Nos. 40, 180, and 181) were analyzed, and good agreement was obtained between the results from the proposed slurry sampling method and the certificate values.
提出了一种基于悬浮液进样，使用配备横向加热石墨管原子化器的原子吸收光谱仪测定煤样中铅、镉和铜的方法。通过将样品直接称入自动进样杯（5 - 30毫克）并加入1.5毫升由5% v/v硝酸、0.05% Triton X - 100和10%乙醇组成的稀释剂混合物来制备悬浮液。在测量前通过手动搅拌使悬浮液均匀化。还研究了使用超声搅拌进行悬浮液均匀化以作比较。研究了粒径和不同稀释剂组成对悬浮液制备的影响。根据热解曲线和原子化曲线优化了温度程序。比较了添加和不添加钯 - 镁改性剂时的吸光度特性。发现使用0.05% m/v的钯和0.03% m/v的镁对稳定镉和铅效果令人满意。采用水溶液标准进行校准。此外，应用传统的酸消解程序来验证悬浮液进样的效率。当粒径减小到<37微米时，分析物的回收率更高。分析了几种有证煤标准物质（BCR编号40、180和181），所提出的悬浮液进样方法的结果与证书值之间取得了良好的一致性。
