Nano-particle analysis using dwell times between 10 μs and 70 μs with an upper counting limit of greater than 3 × 10⁷ cps and a gold nanoparticle detection limit of less than 10 nm diameter

Abstract

A high sensitivity magnetic sector ICP-MS has been used in single particle mode with microsecond dwell times and particle detection limits of <10 nm.

Performance of sp-ICP-TOFMS with signal distributions fitted to a compound Poisson model

“…Recall that the mass content scales with the cube of the diameter, so a 10 nm diameter Au NP, which is only 5 times smaller in diameter than a 50 nm diameter Au NP, contains little mass ($10 ag) compared to a 50 nm Au NP ($1260 ag). To date, the smallest detectable Au NPs are between 4-7 nm in diameter, 15,16 and in order to measure NPs with half this diameter, one would require 8-times higher sensitivity. Near the size detection limit, particle signals are, by denition, similar in signal intensity to background signals, so data processing algorithms used to discriminate NP and dissolved background signals are critical.…”

Single particle inductively coupled plasma mass spectrometry: investigating nonlinear response observed in pulse counting mode and extending the linear dynamic range by compensating for dead time related count losses on a microsecond timescale

“…18 Shaw and Donard instead utilized an unmodied sector-eld ICP-MS instrument featuring a pulse-only detector with fast detection electronics to overcome nonlinear response. 19 With a dead time of less than 6 ns (usually 30-50 ns), the relative mass range covered (q m : 500) is one of the largest and the sensitivity achieved (LDR: 5-40 nm) among the highest reported to date for the analysis of AuNP. Rush et al recently explored an inherently different approach: "Collisional dampening via addition of a collision gas" 20 allowed to prolong the average cloud duration from <2 ms to >10 ms, ultimately extending the LDR for AuNP analysed in pulse-counting (PC) mode from 20-60 nm (q m : 27) to 20-80 nm (q m : 64).…”

“…21,22 According to some of the ndings cited above [13][14][15][16][17] and two further studies that simulate vaporization and diffusion rates of single particles 23,24 it may need to be considered even for much smaller NP. However, the fact that linearity can be regained by attenuating the signal, 18 utilizing a detector with shorter dead time, 19 or extending the ion cloud duration 20 (i.e., aer the ions have been sampled) supports a different theory: nonlinear response of the pulse counting signal to particles within the nanometre size range is most likely attributable to count losses caused by a nite dead time of the detection electronics.…”

A quantitative nanoparticle extraction method for microsecond time resolved single-particle ICP-MS data in the presence of a high background

“…the ion signal duration for one 60 nm Ag NP was approximately 500 ms in our previous study), 10 the choice of an appropriate DT is crucial to ensure a correct detection. The use of a DT on the microsecond time scale allows acquiring several data points per NP [18][19][20][21][22][23][24][25][26] and helps to avoid incorrect detection, when e.g. one NP event is split between two DTs (split-particle event).…”

“…20 A different approach reported by Donard et al utilizes the detection of peak maxima. 24,25 In the present study, we report a data processing method based on Poisson statistics for simultaneous quantication of NPs and dissolved ions (recorded with a prototype msDAQ). The method is rapid and can be used to process ICP-MS measurements of any duration.…”