Quantum dots are 5-nm mixed-metal nanoparticles engineered for enhanced electronic and optical properties, and their release into aquatic environments may be possible through industrial process wastes or disposal of consumer products.  Both the individual nanoparticles and heavy metals released upon dissolution may be toxic to aquatic organisms.  In order to detect and quantify metals across both phases, analytical chemical techniques must first separate the nanoparticulate and dissolved forms, but conventional filtration modes can be difficult or time-consuming for particle sizes 10 nm or less.  A more rapid quantification method for the measurement of &lt;10 nm nanoparticles has been developed using size-exclusion chromatography with inductively coupled plasma – mass spectrometry (SEC-ICP-MS).  Separation of nanoparticulate and dissolved forms was achieved within ten minutes only when using a 125-angstrom pore size SEC column with an eluent composition designed for maximum quantum dot and cation recovery.  Detection limits for multiple metals for both phases were typically 1-10 ppb and about one order of magnitude higher than those measured without SEC.  An alternative method, single-particle ICP-MS, was found to be insensitive to quantum dots.  SEC-ICP-MS was used to monitor CdSe/ZnS quantum dot dissolution facilitated by protons and organic ligands, and dissolution of the outer ZnS shell preceded release of core CdSe elements.  SEC methods with faster analysis times are expected to expedite nanoparticulate and quantum dot analysis in waste streams, natural waters, or laboratory experiments.

Characterization of quantum dot suspensions with SEC-ICP-MS

249th National Meeting (2015)

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