Development of Analyical Methods of Carbon Nanomaterials by Direct Analysis in Real Time (DART) Ion Source with High Resolution Full Scanning Mass Spectrometry

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Research article

Journal of the Korean Society for Environmental Analysis 2013;16(1):62-70.

DART 이온 소스 및 고분해능 질량분석방법에 의한 탄소계 나노물질의 성분 분석법

최원석¹, 최재원²

¹한국수자원공사 수자원연구원
²K-water 수질분석연구센터

Abstract

Concerns on the production, use and occurences in the environment of nanomaterial are increasing. Fast determination of nanomaterial from various environmental matrices are requiring to understand their fates in water, soil and biological tissues. In this study, ambient ionization technique with mass spectrometry was used as a fast identification tools for fullerenes C 60 , C 72 C 84 and single (SW), double (DW), multi (MW) wall carbon nanotubes (CNTs). For this performance, direct analysis in real time (DART) with Orbitrap high resolution mass spectrometer was applied. For DART, optimized condition for ionization temperature and time were set at 400~500oC and 1 min. Resolution, mass scan range and accuracy of Orbitrap MS were operated at 50,000,100~1,100 amu and 5 ppm, calculated parts per million unit of monoisotope, respectively. Standard fullerene C 60 , C 72 and C 84 were successfully ionized by DART source at high temperature. Molecular and their isotopes were detected with high mass accuracy for 0.55~1.77 ppm. Fullerenes were not found in sludge samples from drinking water treatment plants. For CNTs, specific m/z ions were not differentiated among SW, DW and MW-CNT standards and 36 sludges. After background mass removal, major 60 m/z ions were used for statistical analysis. Cluster between SW, DW, MW-CNT standard and sludges were separated in principal component analysis (PCA). Further, scanning electron microscopy (SEM) was used to supplement the qualitative method above. There was no similarities between CNT standard samples and sludges. This methodology suggesting very fast and accurate ionization and identification method for carbon nano-materials. Further, this is the first report of desorption ionization technique to carbon nanotube analysis for identification.

Key Words: DART, Orbitrap MS, Fullerene, CNT, Nano material