A nanoparticle is defined by the IUPAC as "a particle of any shape with dimensions in the 1 × 10−9 and 1 × 10−7 m range". Put simply that means a particle of any material with dimensions below 100nm in size. The use of nanomaterials in consumer products has increased drastically in recent years due to the special properties often exhibited by materials at the nanoscale. Nanoparticles are now widely used as anti-bacterial agents in consumer products and healthcare, food additives, sunscreen and cosmetics, life science research, drug delivery and bioimaging, catalysts and coatings, electronics, optics and materials technology.
ICP-MS has come to the forefront as an analytical tool with unique capabilities for the detection and quantificaiton of various nanoparticles. Using the high sensitivity and fast dwell times of the Agilent 8900 triple quadrupole ICP-MS we have developed methods for the quantification of nanoparticles in terms of particle size, number and physical state (dissolved/ ionic). ICP-MS is particularly suited to the analysis of nanoparticles in complex matrices due to it's element specificity, an attribute lacking in other nanoparticle analytical techniques.
The basic priciples of SP-ICP-MS are relatively simple:
•Nanoparticles entering the plasma are atomized and the individual atoms ionized resulting in a cloud of ions
•The density of ions in the ‘ion cloud’ is high resulting in an elevated signal pulse compared to the background
•These signal pulses can then be converted to a 'size' by careful calibration and use of standard reference nanoparticles
ICP-MS has come to the forefront as an analytical tool with unique capabilities for the detection and quantificaiton of various nanoparticles. Using the high sensitivity and fast dwell times of the Agilent 8900 triple quadrupole ICP-MS we have developed methods for the quantification of nanoparticles in terms of particle size, number and physical state (dissolved/ ionic). ICP-MS is particularly suited to the analysis of nanoparticles in complex matrices due to it's element specificity, an attribute lacking in other nanoparticle analytical techniques.
The basic priciples of SP-ICP-MS are relatively simple:
•Nanoparticles entering the plasma are atomized and the individual atoms ionized resulting in a cloud of ions
•The density of ions in the ‘ion cloud’ is high resulting in an elevated signal pulse compared to the background
•These signal pulses can then be converted to a 'size' by careful calibration and use of standard reference nanoparticles
Individual nanoparticles are ionised in the plasma of the ICP-MS resulting in an ion cloud which is then detected as an elevated spike in the transient signal data collected by the instrument. 'bigger particles' result in bigger spikes. Through careful calibraiton and data processing the signal spike can be converted to a particle size.
One factor of critical importance to the quantification of nanoparticles by ICP-MS is the 'dwell time' of the detector. Older instruments with minimum dwell times in the range of 10 ms are prone to capturing multiple nanoparticle events in a single 'snapshot' from the detector. This results in signal spikes of increased intesity bieng interpeted as a single particle event. Newer ICP-MS instruments are capable of much shorter dwell times. The use of shorter dwell times helps lower the possibility of multiple particle events. An additional capability of the Agilent 8900 when used with a 0.1ms dwell time is the integration of multiple data points over a signal particle event allowing for more accurate size characterization and the analysis of samples with a broader range of particle concentrations.
