Speciation Analysis Of Arsenic And Selenium In Atmospheric Particulate Matters

Arsenic and selenium species in atmospheric particulate matter were analyzed by liquid chromatography inductively coupled plasma mass spectrometry（LC-ICPMS）coupling system.The separation and detection conditions were optimized.Arsenic and selenium species were rapidly separated and sensitively detected.The atmospheric particulate matter（PM）samples from September 2017 to August 2018 in four seasons were analyzed by LC-ICPMS.The seasonal distribution characteristics of arsenic and selenium species in atmospheric particulate matter and the correlation between species and particle sizes(TSP,PM_2.5 and PM₁₀)were discussed.（1）Anion exchange chromatography and cation exchange chromatography were coupled with inductively coupled plasma mass spectrometer（ICPMS）detector.Arsenite（As（III））,arsenate（As（V））,monomethylarsenic（MMA）,dimethylarsenic（DMA）and trimethylarsine oxide（TMAO）,Se（IV）and Se（VI）were separated and detected by the developed methods.The conditions of mobile phase including concentration,p H and gradient elution were optimized.The interferences of compound ions composed of ⁴⁰Ar and ³⁵Cl on ⁷⁵As and ⁸²Se were reduced by adding helium gas into the collision cell.The detection limits and sensitivity were obviously improved.The detection limits of arsenic and selenium were 0.2-0.32 ng/g and 0.79-1.21 ng/g,respectively.（2）The established method was successfully applied to analyze atmospheric particulate matter samples from four seasons（September 2017 to August 21018）in Baoding city.Trimethylarsine oxide（TMAO）was found in the PM samples.As（V）was the main species in PM with a small amount of As（III）and TMAO.DMA was only found in summer samples,while MMA was not detectable in all samples.Se（IV）is the main species in PM except for summer.The speciation of selenium in summer is contrary to that of other seasons.（3）The established method was successfully applied to analyze atmospheric particulate matter samples from four seasons（September 2017 to August 21018）in different particle matters in Baoding city.Trimethylarsine oxide（TMAO）was found in the PM samples.As（V）was the main species in PM with a small amount of As（III）and TMAO.DMA was only found in PM₁₀ and PM_2.5 samples,while MMA was not detectable in all samples.Se（VI）was the main species of all particle sizes in summer,and there were significant differences between PM_2.5 and TSP in spring,autumn and winter（p<0.01）,while there were no significant differences between particle sizes in other seasons Moreover,the smaller the particle size,the higher the water-soluble arsenic and selenium content.