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Abstract. Hyphenated laser ablation-mass spectrometry instruments have been recognized as useful analytical tools for the detection and chemical characterization of aerosol particles. Here we describe the performances of a laser ablation aerosol particle time-of-flight mass spectrometer (LAAPToF-MS) which was designed for aerodynamic particle sizing using two 405 nm scattering lasers and characterization of the chemical composition of single aerosol particle via ablation/ionization by a 193 nm excimer laser and detection in a bipolar time-of-flight mass spectrometer with a mass resolving power of m/ m > 600.We describe a laboratory based optimization strategy for the development of an analytical methodology for characterization of atmospheric particles using the LAAP-ToF-MS instrument in combination with a particle generator, a differential mobility analyzer and an optical particle counter. We investigated the influence of particle number concentration, particle size and particle composition on the detection efficiency. The detection efficiency is a product of the scattering efficiency of the laser diodes and the ionization efficiency or hit rate of the excimer laser. The scattering efficiency was found to vary between 0.6 and 1.9 % with an average of 1.1 %; the relative standard deviation (RSD) was 17.0 %. The hit rate exhibited good repeatability with an average value of 63 % and an RSD of 18 %. In addition to laboratory tests, the LAAP-ToF-MS was used to sample ambient air during a period of 6 days at the campus of Aix-Marseille University, situated in the city center of Marseille, France. The optimized LAAP-ToF-MS methodology enables high temporal resolution measurements of the chemical composition of ambient particles, provides new insights into environmental science, and a new investigative tool for atmospheric chemistry and physics, aerosol science and health impact studies.

Highly homogeneous multi-element gelatin calibration standards were fabricated for quantitative LA-ICP-MS bioimaging. Heterogeneity issues caused by the so-called "coffee-stain" and/or "Marangoni" effects were found to be element-dependent but could be circumvented by careful selection of drying/setting conditions. A micro-homogeneity test was developed for certification of the standards.

In this work, pre- and postacquisition procedures for enhancing the lateral resolution of laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) in two- and three-dimensional (2D, 3D) nuclide distribution mapping beyond the laser beam waist are described. 2D images were constructed by projecting a rectangular grid of discrete LA positions, arranged at interspacings smaller than the dimensions of the laser beam waist, onto the sample surface, thus oversampling the region of interest and producing a 2D image convolved in the spatial domain. The pulse response peaks of a low-dispersion LA cell were isolated via signal deconvolution of the transient mass analyzer response. A 3D stack of 2D images was deconvolved by an iterative Richardson-Lucy algorithm with Total Variance regularization, enabling submicrometer image fidelity, demonstrated in the analysis of trace level features in corroded glass. A point spread function (PSF) could be derived from topography maps of single pulse craters from atomic force microscopy. This experimental PSF allows the approach to take into account the laser beam shape, beam aberrations, and the laser-solid interaction, which in turn enhances the spatial resolution of the reconstructed volume.