Laser Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) are used simultaneously for spatially resolved mapping of major and trace elements and isotopes within a Bastnäsite rare earth ore sample.

A method that integrated thin-layer chromatography (TLC) with femtosecond laser ablation−inductively coupled plasma−mass spectrometry (fs-LA−ICP−MS) was developed for the determination of the proportionality of vanadium/nickel in the asphaltene fraction of crude oils. TLC is easy and fast to implement for separation of crude oil components requiring minimal amount of solvents, and fs-LA−ICP−MS allows for direct analysis of the TLC plates without any additional sample preparation. This method was tested on Venezuelan crude oil samples and their isolated asphaltenes. The results correlated well to those obtained using a traditional method for asphaltene analysis involving separation and digestion with measurements by inductively coupled plasma−optical emission spectroscopy (ICP−OES). The combination of TLC with fs-LA−ICP−MS provided fast and reliable measurements of V/Ni proportionality in asphaltene and directly from the crude oil without solvent-exchange processes.

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The precision and accuracy of the 238 U/ 232 Th ratio were evaluated from liquid nebulization and direct solid sampling repetitive pulsed laser ablation. Nanosecond and femtosecond pulsed lasers at 266 nm wavelength were utilized for the ablation studies. The ICP-MS and sampling parameters were optimized for each procedure; flow rates, gases, laser energy and other parameters were optimized for the particular sampling approach and therefore will not be the same. The work is not a comparison per se but represents performance metrics for three optimized sampling modalities. As expected, nanosecond pulsed ablation provided the greatest inaccuracy (430%) from the nominal 238 U/ 232 Th bulk ratio. This deviation from bulk ratio is attributed to incomplete vaporization of large particle agglomerates produced by nanosecond laser ablation. Femtosecond pulsed ablation provided inaccuracy (B1-3%) approaching that of liquid nebulization (B1%). In terms of temporal relative standard deviation (TRSD) and relative standard deviation (RSD), liquid nebulization provided the best precision for the 238 U/ 232 Th ratio (TRSD B3-5%, RSD B0.2-0.6%), femtosecond laser ablation (TRSD B5-12%, RSD B1%) and nanosecond laser ablation (TRSD B25-48%, RSD B9-12%). Laser ablation requires less sample to achieve these performance metrics, in some cases less than a factor of 100-times depending on the entrainment and transport efficiency.