Parallel flow ablation cell for short signal duration in LA-ICP-TOFMS element imaging

Abstract

The acquisition speed in laser ablation inductively coupled plasma mass spectrometry element imaging depends significantly on the laser aerosol transport system. The faster the aerosol washout, the faster the acquisition can be carried out. Here, we introduce a modified ablation cell based on the tube cell design for laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) element imaging which provides shorter signal durations. The parallel flow ablation cell (PFAC) included a recess in the cover for improved gas flow pattern at the ablation site and achieved signal durations of 0.25 ms (FW0.1M) for ⁴⁴Ca and 0.29 ms (FW0.1M) for ²³⁸U on NIST SRM 610 using a laser ablation repetition rate of 100 Hz. Shortest signal duration was achieved using an inner cell to sample surface distance (CSD) of 700 μm, which is several times larger compared to previous fast washout ablation cells published and shows high tolerance to variations in the CSD. A shift in arrival time from the ablation to TOFMS extraction was observed when comparing light to heavy ions. A H₂ collision and reaction cell was not able to correct for this shift and lead to extended signal durations, but still very short signals of approximately 0.4 ms (FW0.1M) were observed. The robustness of the washout in a wide range of CSD makes the PFAC a promising ablation cell for fast aerosol transport and quasi-simultaneous detection of ions using an ICP-TOFMS and element imaging using a ≥1000 Hz laser ablation rate while maintaining the possibility for pulse-to-pulse signal separation.