A New Mapping Protocol for Laser Ablation (withFast‐Funnel) Coupled to aTime‐of‐FlightMass Spectrometer (LA‐FF‐ICP‐ToF‐MS) for the Rapid, Simultaneous Quantification of Multiple Minerals

Abstract

Although in situ analysis by LA-ICP-MS is considered a rapid technique with minimal sample preparation and data reduction, mapping areas of millimetres in size using a small beam (< 15 μm) can be time consuming (several hours) when a quadrupole ICP-MS is used. In addition, fully quantitative imaging using internal standardisation by LA-ICP-MS is challenging in samples with more than one mineral phase present due to varying ablation rates. A new protocol for the quantification of multiple coexisting phases, mapped at a rate of about 12 mm 2 h -1 and a resolution of 12 μm × 12 μm per pixel, is presented. The protocol allows mapping of most atomic masses, ranging from 23 Na to 238 U, using a time-offlight mass spectrometer (ICP-ToF-MS, TOFWERK) connected to a 193 nm excimer laser. A fast-funnel device was successfully used to increase the aerosol transport speed, reducing the time usually required for mapping by a factor of about ten compared with a quadrupole ICP-MS. The lower limits of detection for mid and heavy masses are in the range 0.1-10 μg g -1 , allowing determination of trace to ultra-trace elements. The presented protocol is intended to be a routine analytical tool that can provide greater access to the spatial distribution of major and trace elements in geological materials.

Atomic spectrometry update – a review of advances in environmental analysis

“…Although the ICP-TOF-MS technique had lower sensitivity and narrower linear dynamic range than SF-ICP-MS, the main host mineral phase(s) of an element could be readily identified and the major and trace element abundances in the phase(s) could be quantified with an accuracy approaching that of the spot analysis. Savard et al 231 described a new protocol for producing elemental distribution maps (Na to U) across a variety of minerals. They used a LA-ICP-TOF-MS instrument incorporating a fast-funnel device to increase the aerosol transport speed.…”

Elemental Characterization of Iron Meteorites Solely Based on LA-ICP-MS

“…Normalization is mandatory when acquiring elemental maps of multiphasic samples that otherwise would require the mass fraction value of an internal standard for each phase. 25 Limits of Detection. Limits of detection (LOD) were calculated in iolite 4, which applies the equations described by Longerich et al 29 In this approach, as the amount of material ablated in LA sampling is often significantly different for each analysis, the LOD must be calculated for each acquisition.…”

“…To achieve it, we used the 3D trace element data reduction scheme (DRS) available on iolite 4 software after calibrating the instrument using both NIST SRM 612 and the North Chile (aka Filomena). Instead of the conventional instrumental drift approach, we applied a normalization that considers the sum of Fe, Ni, and Co mass fractions as 100%, eliminating the need for an independent measurement of Fe or Ni by another technique, as also demonstrated for other matrices. , In this way, Fe and Ni mass fractions can also be determined, yielding a complete set of elements needed for the chemical characterization of iron meteorites. This new calculation scheme was also applied to generate elemental imaging maps from the LA-ICP-MS data, expanding the versatility of the method.…”

Time resolved trace element calibration strategies for LA-ICP-MS

“…An approach for normalisation using criteria based on background-subtracted count rates to adjust normalisation parameters for selected phases is presented. The sample is a nelsonite from the Sept-Îles mafic intrusion 22 and was analysed by LA-ICP-TOF-MS at LabMaTer (UQAC) following the procedures described in Savard et al 23 This example does not serve to demonstrate the accuracy of the normalisation criteria approach (which has been demonstrated elsewhere 13 ), but rather demonstrates the concept of being able to use the sum normalisation approach in an imaging experiment by defining phases based on counts rates.…”

“…Using the criteria sum normalisation approach avoids this analytical artefact to produce more accurate concentration data for imaging experiments. This approach is discussed in more detail in Savard et al 23…”