悬浮液进样电感耦合等离子体发射光谱中颗粒的输运和蒸发行为

Transportation and Evaporation Behavior of Suspension Particle for Slurry Nebulization Introduction in Inductively Coupled Plasma Optical Emission Spectrometry

以碳化硼为例,研究了悬浮液雾化进样中的粒子在传输和蒸发过程中的行为,并对分析结果出现负偏离的原因进行了详细探讨。对比悬浮液颗粒的原始粒径分布和经过传输过程后的粒径分布,获得到达等离子体的颗粒粒径上限小于10μm。样品中存在的部分超大粒径的颗粒(d≥10μm)会严重影响可传输区域颗粒(d<10μm)的质量运输效率,颗粒质量传输效率与其粒径大小呈反相关。实验和理论计算发现,碳化硼颗粒完全蒸发的的粒径上限约为2.0μm,粒径对颗粒蒸发的影响远比其对传输效应的影响显著。调整雾化气流速可以改善样品的分析结果,但是依然低于碱熔法得到的定量分析结果。因此,采用悬浮液雾化进样电感耦合等离子体光谱标准水溶液校准分析此类样品时,采用研磨手段使样品粒径分布在材料能够完全蒸发的极限以内是获得准确分析结果的关键。

The behavior of boron carbide slurry particles in the transportation process and vaporization process of suspension nebulization inductively coupled plasma optical emission spectrometry（ICP-OES） was investigated to study how the negative deviation in the determination results of advanced ceramic materials by using slurry nebulization ICP-OES with aqueous standards calibration came into being.Both the particle size distribution of the original ceramic powders and the particle size distribution after pneumatic nebulization of slurries were determined.Experimental results showed that the upper limit of the particle which can be transported in to the plasma torch was about size of 10 μm.The particle which size was much more than 10 μm in the sample would adversely affect the mass transport efficiency and an anticorrelation exists in the mass transport efficiency vs.the particle size.Both the experiment and calculation results showed that the upper limit of the boron carbide particle which can be completely evaporated in the plasma was about size of 2.0 μm.Thus the impact of particle size on atomization efficiency was more than on that of the mass transport efficiency.The particle evaporation could be improved by the use of a relative low nebulization gas flow rate,but the analysis results were still lower than those obtained by the alkali fusion method.Consequently,suitable grinding techniques to reduce sample particle to the appropriate size,in which the particle could be completely evaporated in the plasma,was critical for advanced ceramic materials using slurry nebulization ICP spectrometry with aqueous standard calibration.