Determination of metallic nanoparticles in air filters by means single particle inductively coupled plasma mass spectrometry

Single particle inductively coupled plasma mass spectrometry (spICP-MS) has been explored for the determi-nation of metallic nanoparticles (NPs) in air. Different extraction strategies (i.e., direct immersion, hard cap espresso, ultrasound-assisted and microwave-assisted extraction) and extracting solvents (i.e., citric acid, triso-dium citrate, potassium nitrate, sodium nitrate, thiourea, disodium pyrophosphate and ammonium hydroxide) were investigated for platinum and gold NPs recovery from glass and microquartz fiber filters with a nominal size cut-off of 300 nm. Results show that metallic NPs are preserved and quantitatively extracted from the filter in 4 min inside an 800 W microwave oven by using 40 mL of a 2.0% w w-1 NH4OH solution. For the remaining extraction procedures, either incomplete recoveries or NPs degradation occur. As regards the influence of filter material, microquartz fiber affords better NPs capturing performance than glass fiber ones, enabling the quan-tification of NPs with diameters above 28 nm. This methodology has been successfully applied to determine PtNPs in filters from environmental monitoring stations and to gain insight into NPs transport through ICP-MS sample introduction system. Care should be taken during spICP-MS calibration since biased results might be obtained due to differences on NPs transport efficiency between standards and samples.

Automated summary

Single particle inductively coupled plasma mass spectrometry (spICP-MS) has been used to determine metallic nanoparticles (NPs) in air. Different extraction strategies and extracting solvents were investigated, and a method for extracting metallic NPs from filters in 4 minutes was developed. The study also found that microquartz fiber filters had better NPs capturing performance. This method has been successfully applied to detect NPs in environmental monitoring stations.