Rapidly growing application of carbon nanotubes (CNTs) for industry and consumer products will lead to their accumulation in the environment. Protection of food safety from contamination by CNTs and best-practice management of agricultural application of CNTs require unambiguous quantification of CNTs in agricultural plants. Herein, a novel method of digestion coupled with programmed thermal analysis (PTA) was developed for quantitative analysis of multiwall CNTs (MWCNTs) in plant (lettuce) tissues. MWCNT-bound carbon was linearly correlated with elemental carbon (EC) detected by PTA, including EC1(58.46 ± 24.63%) (combusted under 580°C) and EC2 (41.5 ± 24.64%) (740°C) corresponding to less stable and stable carbon, respectively. The background plant materials can interfere EC quantification of CNTs in the plant tissues, as about 15% of the total biomass from plant tissues was charred during the thermal analysis. Sequential digestion with concentrated HNO3 and H2SO4 effectively minimized the interferences caused by the lettuce tissues, reducing the background EC generated from leaf tissues to 0.53 ± 0.13 µg C/g. By coupling digestion with PTA analysis, our method achieved a detection limit of 28 µg CNT-C/g plant tissues. Later, the method was validated by measuring translocated CNTs in leaf tissues of lettuce (Lactuca sativa) hydroponically incubated with CNT solution. This novel method can be applied for unambiguous quantification of CNTs in plant tissues at low concentrations and be useful for understanding and managing risk of CNTs exposure through agricultural plants.

Quantification of multiwall carbon nanotubes in plant tissues using digestion-coupled programmed thermal analysis

255th National Meeting (2018)

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