Abstract
Laser ablation is most frequently applied to the analysis of solid samples. A combination of laser ablation (LA) with inductively coupled plasma mass spectrometry (ICP-MS) is one of the most powerful analytical techniques. LA-ICP-MS is advantageous because of its direct solid sampling capability, high sensitivity, fast analysis, microanalysis, and depth profiling capabilities. In this study, dried microdroplets of sample, previously mixed with methylene blue matrix, were quantitatively ablated from a PTFE (polytetrafluoroethylene) filter. The developed method needed nearly no sample pre-treatment for determining elements, therefore, the losses due to the formation of volatile compounds and presence of contaminants could be negligible. In addition, up to fifteen elements on a single filter sample can be determined within 5 min. It was found that a 213 nm laser with 100% laser energy and 2 mm defocus distance, at 20 Hz repetition rate and 8 seconds dwell time can ablate the dried droplet samples appropriately. Both the external standard and standard addition were applied for quantification by LA-ICP-MS. A good precision (RSD<10 %) and high recovery (95-105 %) can be obtained in this research. The high correlation coefficients (0.9922-0.9998) and low detection limits (0.04-0.81 ng mL-1) for most elements of interest showed that this method would be useful for future quantification in any kind of liquid samples. The proposed method was applied to real environmental samples, such as bottled water, tap water, swimming pool water, lake water and simulated wastewater. The results indicate that both inorganic salts and organic matrics cause negligible effect on signals even in high concentration.