2022 Volume 71 Issue 7.8 Pages 377-390
Novel inorganic/organic analytical systems for ultrasmall samples such as materials at the sample surface or single cell/nanoparticles have been developed using atmospheric plasmas, which have various gas temperatures from room temperature to thousands of K, and their application for various fields have been studied. To achieve highly sensitive and prompt analysis of materials on the sample surface, the atmospheric plasma soft-ablation method (APSA) was developed by using damage-free plasma, which has a temperature close to room temperature and no risk of electrical shock, as a sample desorption/ionization source for ambient mass spectrometry. The APSA method has allowed inorganic/organic analysis of materials on heat-sensitive substrates like living skin. In an application of APSA, a gas-cylinder-free plasma desorption/ionization system for on-site mass analysis of chemical warfare agents (CWAs) was developed and HN3, GF, GA, and VX were successfully measured with LODs at the pmol level. To analyze elements contained in a single cell or single particle from ultra-trace levels of ag (10−18 g) to large amounts, the droplet direct injection nebulizer (D-DIN) and signal acquisition/processing method for D-DIN were developed. These techniques were applied for inductively coupled plasma mass spectrometry (ICP-MS) to build a single cell/particle analytical system. Elemental analysis of single unicellular algae was performed by this system and LODs at the ag level were achieved. Additionally, a high-power pulsed microplasma was applied as an excitation source for D-DIN and the resulting LODs obtained were at the fg level.
