Paraytec has released an application note that shows how its Actipix HT nano-sizing system has been used to determine the hydrodynamic radius of a series of quantum dot and nanoparticle samples.
Quantum dots are new forms of semiconductors that model atoms.
Being only nanometers in size and offering high quantum efficiency, quantum dots are opening up applications in medical imaging, electronics and optical technologies.
Determining the hydrodynamic radius of synthesised samples is important as size has a significant effect on the more subtle effects offered by quantum dots.
Applications data presented on the Paraytec website shows how researchers were able to achieve excellent correlation between experimental and expected values of quantum dot hydrodynamic radii with typical analysis times of less than 10 minutes.
Prof Stephen Evans of the Department of Physics at Leeds University said: 'This approach promises to offer significant benefit to the quantum dot and nanoparticle manufacturing community as it has the potential to enable rapid, online size determination in a fraction of the time offered by current methods such as transmission electron microscopy [TEM].' The high-precision Actipix HT nano-sizing system consists of a precision nano-injector, an autosampler and a detector.
Samples are typically stored in the autosampler prior to the injection of a few nanolitres of each sample into a fused capillary.
A plug of the sample, typically 20-100nL, was injected at the capillary inlet of a specially designed sizing cartridge and was driven by the application of external pressure along the capillary.
Ultraviolet (UV) absorption of the sample was recorded in the first and second detection window using the Actipix D100 detector.
While the area of each peak is the same, the widths of the peaks are different: the signal from the second window has a greater width and lower amplitude because of Taylor dispersion.
The peaks were analysed with an appropriate peak fitting function using software supplied with the system.
The area under the peak corresponds to the amount of the quantum dot injected.
The standard deviations are used to calculate the hydrodynamic radius of the sample.
Paraytec's Actipix D100 quantitative UV area imaging system is claimed to provide superior performance over conventional particle measuring techniques, which cannot effectively measure down to sub-20nm sizes.
