Elemental Fractionation Studies of Biological Samples UsingLaser Ablation Inductively Coupled Plasma Mass Spectrometry / 分析化学

ABSTRACT

The ablated aerosols of biological matrix sample were studied using 213 nm nanosecond laser ablation system.The stable signal intensity and high sensitivity were obtained when the laser energy was 25%, the spot size was 200 μm, the scan rate was 20 μm/s, the frequency was 20 Hz and the carrier gas was 700 mL He + 700 mL Ar.Relative fractionation index of 56 elements were investigated and 31P as the internal standard element was selected under the optimized laser ablation conditions.The results showed that particle size of the biological sample was 3 μm, which was larger compared with NIST 610 sample.Element fractionation in biological sample was smaller than in glass sample, and relative fractionation index of most elements attained 1.0 ± 0.1.Element fractionation mechanism of biological sample was discussed.The possible reason why the relative fractionation index in biological sample with large particle size did not significantly increase compared to the glass sample is that the 3-μm particles entered into ICP can be atomized.On the other hand, enrichment effect for large ablation particles was relatively small.Further study of the influence factors of fractionation effect indicated that, the fractionation effect had relations with laser ablation energy, laser frequency and scan rate, negatively relation with the oxide boiling point, and positively relation with oxide bond energy and ionization energy.