Analytical Sciences, Contributed Talk (15min)

Studies on a downward inductively coupled plasma time-of-flight mass spectrometer to analyze droplets carrying particles or cells

T. Vonderach1, V. Wyss1*
1Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich

Recently, the first downwardly-oriented ICP-MS analyzing monodisperse droplets was reported. [1] The sample drop introduction system was further developed and the quadrupole was replaced by a time-of-flight mass analyzer [2], which enabled to record short transient signals obtaining multi-element information from droplets, particles and cells. The idea of a droplet desolvation system by Gschwind et al. [3] as well as Alavi et al. [4] was adapted and a modified falling tube made of glass equipped with several gas inlets for Helium and Argon was designed. The sample supply system was wrapped into heating tape so that it allowed operation at elevated temperatures (approximately 100°C), which further accelerated the droplet evaporation process as predicted by Koch et al. [5]

A time-resolved droplet throughput of up to 1000 Hz was recorded for 70 µm sized droplets. Furthermore, droplets up to 90 µm in size could be detected successfully, which has never been reported for ICP-MS studies. Note that the maximum droplet size was limited by the capabilities of the microdroplet generator used. Single cells were extracted from mouse tissue, stained with Ir intercalator as well as several surface markers, transported via microdroplets and finally analyzed in the ICP. Data on droplet throughput, droplet size, jitter, elemental ratios and single cell studies is provided. Furthermore, cell-droplet events were recorded with a time resolution of 33 µs and the corresponding signal structures are discussed in detail.

[1] Thomas Vonderach, Bodo Hattendorf, Detlef Günther, Analytical Chemistry 2021, 93 (2), 1001-1008.
[2] Olga Borovinskaya, Bodo Hattendorf, Martin Tanner, Sabrina Gschwind, Detlef Günther, Journal of Analytical Atomic Spectrometry 2013, 28 (2), 226-233.
[3] Sabrina Gschwind, Luca Flamigni, Joachim Koch, Olga Borovinskaya, Sebastian Groh, Kay Niemax, Detlef Günther, Journal of Analytical Atomic Spectrometry 2011, 26 (6), 1166-1174.
[4] Sina Alavi, Xiaoman Guo, Seyyed Morteza Javid, Ali Ebrahimi, Javad Mostaghimi, Analytical Chemistry 2020, 92 (17), 11786-11794.
[5] Joachim Koch, Luca Flamigni, Sabrina Gschwind, Steffen Allner, Henry Longerich, Detlef Günther, Journal of Analytical Atomic Spectrometry 2013, 28 (11), 1707-1717.