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High resolution, fast and more informative LA imaging with the icpTOF O. Borovinskaya 1 , M. Tanner 1 , R. Belissont 2 , M.C. Boiron 2 , B. Luais 2 , L. Summerfield 3 , S.J.M. Van Malderen 4 , T. Van Acker 4 , F. Vanhaecke 4 1 TOFWERK, 2 Université de Lorraine, 3 ESI, 4 Department of Analytical Chemistry, Ghent University email: [email protected] ► Fast and high resolution imaging is of growing interest for many geological and biological applications, but poses challenges to laser ablation (LA) units and mass spectrometers (MS). ► Recently developed Dual Concentric Injector (DCI) from ESI [1] and Aerosol Rapid Introduction System (ARIS) from Teledyne CETAC Technologies [2] as add-ons to the existing ablation chambers enable rapid aerosol washout of <50 ms and increase imaging speed and signal to noise ratio. ► To utilize these new systems for multi-elemental imaging a mass spectrometer with high acquisition speed and simultaneous detection is required. ► This work demonstrates the coupling of TOFWERK time-of-flight mass spectrometer icpTOF with NWR 213 nm LA system/TwoVol 2 cell/DCI (ESI) and with Analyte G2 LA system/HelEx 2 cell/ARIS (Teledyne CETAC Technologies) for fast and easy imaging at high spatial resolution. Imaging concept -Sensitivity comparable to ICP-QMS -Full mass spectra at 33 kHz -Linear response >1e6 -Mass resolving power >3000 -Interference removal with Q-cell -Matrix removal with notch filter -External hardware triggering Summary Optical and LA-ICP-MS intensity images of juvenile ceriodahnia thin section. Using the icpTOF with the Analyte G2/ HelEx cell/ARIS an area of 600 µm x 500 µm was mapped at 5-µm resolution in only 12 min, with five complete mass spectra recorded for each 5-µm pixel. Ablation was performed at 20 Hz laser frequency, continuously scanning over lines at 100 µm/s. Each laser pulse produced a <50-ms transient signal, and adjacent pulses were resolved from one another. icpTOF acquisition was synchronized with the pulsing of the laser (one pulse/pixel). These juvenile ceriodaphnia (72 hours old) provided by the Ghent University Environmental Toxicology Unit (GhEnToxLab) was exposed to Ni, Cu and Zn at concentrations close to concentrations in contaminated river. After it underwent a glutaraldehyde/formaldehyde fixation in 0.1 M Cacodylate buffer. The samples were treated with uranyl acetate and dehydrated via an ethanol series. Each water flea was embedded individually in Spurr's resin. A 5 µm thick section was produced using a Leica EM UC7 ultramicrotome. ► Rapid aerosol transfer systems resolve individual laser pulses at frequencies > 10 Hz, enabling lateral translation speeds much higher than previously possible. ► icpTOF and laser synchronization on per pixel basis simplifies image reconstruction and provides sharp images with spatially resolved pixels. ► icpTOF measures several full mass spectra per every single pixel, providing higher information density about the sample. icpTOF [1] http://www.teledynecetac.com/product/laser-ablation/aris (accessed on 17.05.2016) [2] D. N. Douglas et.al. Anal. Chem., 2015, 87, 11285-11294 [3] R. Belissont et.al. Geochimica et Cosmochimica Acta, 2014, 126, 518-540 63Cu 73Ge 56Fe 71Ga 118Sn 0.1 mm 107Ag 121Sb 208Pb 115In 31P 24Mg 60Ni 63Cu 66Zn 75As 138Ba 238U 111Cd 23Na Optical and LA-ICP-MS intensity images of Ge-rich sphalerite. Using the icpTOF with the NWR 213/TwoVol 2/DCI (ESI), an area of 750 µm x 1000 µm was mapped at 5-µm resolution in only 50 min, with seven complete mass spectra recorded for each 5-µm pixel. Ablation was performed at 10 Hz laser frequency, continuously scanning over lines at 50 µm/s. Each laser pulse produced a <100-ms transient signal, and adjacent pulses were easily resolved from one another. icpTOF acquisition was synchronized with the pulsing of the laser (one pulse/pixel). This sample was characterized in the previous study [3]. Different mineral zonings were measured at selected 60 µm and 32 µm spots and authors observed enrichment of Ge, Cu, Ga, Sb, and As in one zone and enrichment of Fe, Cd, In, and Sn in another. This high resolution image on one particular sample location provides more detailed information on elemental correlation. Sphalerite mapping with NWR 213/TwoVol 2 cell/DCI Ceriodaphnia imaging with Analyte G2/HelEx 2 cell/ARIS Continuous laser scan Fast transfer of LA plume Time (ms) Synchronized detection of all m/z per pixel Trigger per pulse 0.4 0.3 0.2 0.1 0.0 Signal 80 60 40 20 0 Time (ms) 1 m/z Pixel-resolved images of all m/z Mass spectrum 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 10 1 Signal intensity 250 200 150 100 50 Mass/charge (Th) Transient signal of 1 m/z * X 0.6 mm 0.5 mm 1 mm 0.6 0.5 0.4 0.3 0.2 0.1 0.0 Signal (ions/extraction) 40 35 30 25 20 15 10 Time (ms) 24Mg 31P 65Cu 66Zn 75As Single pixel signal Single pixel signal 0.4 0.3 0.2 0.1 0.0 Signal (ions/extraction) 80 60 40 20 0 Time (ms) 63Cu 74Ge 107Ag 121Sb 208Pb Authors would like to acknowledge ESI and Teledyne CETAC Technologies for providing their laser ablation systems and for fruitful collaboration.
