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Table 2
Measurement techniques for nanoparticles [40].
Technique | Measures | Sample | Sensitivity | Notes |
---|---|---|---|---|
Transmission Electron Microscopy (TEM) | Particle size and characterization | <1 μg has to be prepared as a thin film and be stable under an electron beam and a high vacuum | Down to 1 nm | Additions to TEM can provide more information, e.g. Scanning Transmission Electron Microscopy (STEM). High-Resolution TEM (HRTEM) or in-situ measurements as Environmental TEM |
Scanning Electron Microscopy (SEM) | Particle size and characterization | Sample must be conductive or sputter coated, easier to prepare than TEM sample | Down to 1 nm | Can be used in-situ as Environmental SEM |
Atomic Force Microscopy (AFM) | Particle size and characterization | Samples must adhere to a substrate and be rigid and dispersed on the substrate. The appropriate substrate must be chosen. Air or liquid samples | 1 nm to 8 μm | A form of Scanning Probe Microscopy (SPM). Requires less time and cost than SEM and TEM |
Photon Correlation Spectroscopy (PCS) | Average particle size and size distribution | Sample must be a very dilute suspension | 1 nm to 10 μm | Based on Dynamic Light Scattering, an extension of the technique is Photon Cross Correlation Spectroscopy (PCCS) for high concentration opaque suspensions giving particle size and stability of nanoparticles |
Nanoparticle Surface Area Monitor (NSAM) | Human lung-deposited surface area of nanoparticles | Aerosol, concentrations 0–10,000 μm2/cm3, temp 10–35 °C | Down to 10 nm | Similar to an Electrical Aerosol Detector (EAD) |
Condensation Particle Counter (CPC) | Number of concentrations of particles | Aerosol, concentrations 0–100,000 particles/cm3, can be in a flow, higher temps. to 200 °C possible | 2.5 to >3000 nm | Can be used for a flow, hand held models available |
Differential Mobility Analyzer | Particle size distribution | Aerosol | Down to 3 nm | Can be combined with other techniques to create Tandem DMA or DMPS |
Scanning Mobility Particle Sizer (SMPS) | Particle size distribution | Aerosol, can be a concentrated sample of 1,000,000–2,400,000 particles/cm3 | 3–1000 nm | Uses an electrostatic classifier and a CPC, can also add DMA |
Nanoparticle Tracking Analysis (NTA) | Particle size and size distribution | 500 μl suspension, temp 5–50 °C, wide range of solvents can be used | 10–1000 nm | Use with DLS or PCS |
X-Ray Diffraction (XRD) | Average particle for a bulk sample | Larger crystalline samples (>1 mg) required | Down to 1 nm | Can identify individual crystals |
Aerosol Time of Flight Mass Spectroscopy | Particle size composition | Aerosol | 100–3000 nm | The efficiency of this method is less for smaller particles |
Aerosol Particle Mass Analyzer (APM) | Particle mass | Aerosol sample with particle density approx. 1 g/cm3 | Equivalent to 30–580 nm | Gives only mass information and is not dependent on particle size or shape |
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