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End-to-End Integration of Laser Ablation, ICP–MS, and Data Reduction: A World First!

AuthorDr C. Ashley NorrisNorris [email protected]

IntroductionData reduction of LA–ICP–MS data sets hasbeen realised previously via loosely coupledsystems supplied by a range of differentvendors. While this approach provides

considerable flexibility, that same flexibility canresult in propagation of mistakes due to theonerous requirements of the workflow, such asmanual editing of data files and duplication ofset-up in multiple software packages. Inaddition, the limitations of this approach haveresulted in some laboratories imposingunnecessary limitations on what they believecan be measured during a single analyticalsession.

To address this problem Norris Scientific hasmapped out and implemented the first end-to-end workflow that allows users to set up,execute, and reduce data from any LA–ICP–MSsession without the need to duplicate input oruse spreadsheet software to edit any files.Multiple quantification routines can be easilymixed together, and the not-insignificant risk ofmistakes due to mishandling is eliminated. Allof these advantages allow the analyst to focuson more important aspects of LA–ICP–MS suchas sampling, instrument tuning, andoptimisation of ablation conditions.

While this workflow has been first implementedin GeoStar and LADR, with support for someICP–MS instruments, it is hoped that othermanufacturers will emulate this workflow tothe benefit of the LA–ICP–MS community.

Norris Scientific Application Note — Dr C. Ashley Norris, October 2019 — NSAP19A1

Figure 1. The new workflow enabled by GeoStar paired with LADR data reduction software.

Workflow SummaryPractically all LA–ICP–MS sessions aremeasured by sample-standard bracketingwhere primary standards are measured every45–60 minutes to calibrate the ICP–MSresponse and assess instrument drift over time.Secondary standards can be used in a numberof ways, as either a qualitative check thatquantification can recover known values, ormore quantitatively such as determining matrixcorrection factors (at different spot sizes) ormeasuring excess uncertainty. To assessuncertainty it is desirable to place secondarystandards half way between calibrationstandards, where models of drift will be leastconstrained.

The new workflow (Figure 1) requires the laserablation instrument to send a trigger signal foreach ablation to the ICP–MS, which saves thetime resolved signals from each ablation to aseparate file. Starting with the laser ablationinstrument software (GeoStar in this example),the sample list is defined and transferred overto the ICP–MS instrument via a sample list file.This transfer allows the ICP–MS software to

easily show the sample names and laserconditions and also ensures the acquisitiontime for each sample matches between the twoinstruments.

After the sequence has been ablated, the datareduction software needs information fromboth instruments. The laser ablation softwareprovides the sample type, quant name, and thelaser parameters via the log book file, while themeasured values come from the ICP–MSsoftware via the data files.

Now that the data reduction software has all ofthe information about the sequence, the actualdata reduction can be automated as much aspossible, and the chance of transcription errorsbetween the systems is greatly reduced.

Laser Ablation Instrument: Defining the SequenceThe laser ablation instrument is the naturallocation to set up the ablation sequence. Herethe user has the best opportunity to clearlyidentify each sample and to place each ablationin the correct location. The laser ablationsoftware offers tools to control the geometry ofthe sequence as well as to adjust lightingparameters: improving the chance ofidentifying the sample and material typecorrectly. This is also where the laser conditionsare defined. Of course mistakes can stillhappen, and where possible the user should beassisted by additional information such as BSE1

and CL2 images or X-Ray maps.

As well as defining the sequence, the the laserablation software needs to provide controls toset both the sample type (calibration standard,secondary standard, unknown, etc…) and thename of the quantification routine that will beused to quantify the ablation.

1 Back scattered electron imaging, typically collected on a scanning electron microscope (SEM).

2 Cathodoluminesence imaging, collected on an SEM or a dedicated instrument.


Figure 2. The sequence from GeoStar where the sample type and quant name can be defined.

An example sequence set up in the laserablation software GeoStar is shown in Figure 2.The columns “Type” and “Quant Name” showthe type of ablation and the name of thequantification routine used for data reductionpurposes. This example differentiates betweenquantification of a “basaltic glass” and a generalpurpose “silicate” routine (a fanciful example),but other sequences could use either a singlequantification routine, or many, as dictated bythe application.

The laser ablation software directly exports twofiles: one is the “Universal Log Book” file for useby data reduction software (such as LADR). Thiscontains all of the entries in the sequence,including the sample name (“Comment” inFigure 2), laser conditions, and the quant nameand sample type. The second file is the ICP–MSimport file. This file is saved in the specificformat specified by the ICP–MS manufacturer’scontrol software. Currently GeoStar can exportfiles for use by Agilent Mass Hunter, AnalytikJena ASpect MS, and Thermo Qtegra software.Additional formats will be added to GeoStar onrequest.

ICP–MS: Setting Up The Run TableThe ICP–MS software is the best location foroperating, tuning, and configuring the ICP–MS,but requires duplicated effort to set-up forsamples defined on the laser. To simplify set-upand minimise mistakes, the run table should beimported into the ICP–MS software using a filecreated by the laser ablation softwarespecifically for this purpose.

While the details vary between softwarepackages, all ICP–MS software allows the userto import a run table from an external file. Thefile exported from the laser ablation software isselected, the run table is set-up automatically,and now shows additional metadata such asthe sample name and laser ablationparameters.

In practice, different ICP–MS software packageshandle sample names in different ways. TheMass Hunter software from Agilent allows theuser to specify the file name and the sample


Figure 3. The log book in LADR, imported directly from GeoStar with no manual editing.

name separately. To maintain flexibility theGeoStar software can use a template for the filename, rather than the sample name. Byspecifying the file name in one place it ensuresthere is a perfect match between the UniversalLog Book file and the ICP–MS data files. Using atemplate for the file name is optional, and ifdesired the sample names themselves can alsobe used as the data identifier/file name. Whilethis can only work with Mass Hunter software ifthe sample names are all unique (made easierby the “Auto Numbering” feature in GeoStar),the Qtegra software saves run table entries to a“Lab Book” data file which has no uniquenessrequirement.

While running the sequence it is extremelyuseful to have access to the additional metadata such as the sample name. This ensuresthe user can correctly monitor and assess therun as it progresses, as well as elegantly handleinterruptions if they occur.

Once the sequence has been ablated the datafiles can be exported from the ICP–MS softwarein their preferred format, ready for datareduction.

Data Reduction Software: Pulling it all togetherThe data reduction software (in this exampleLADR) loads the Universal Log Book file as wellas the data files from the ICP–MS. The log bookdefines the role of each ablation, and incombination with the laser conditions and the

quantification routine, most of the datareduction set-up can be completedautomatically (Figure 3).

In practice, the quant name specified duringdefinition of the sequence in the laser softwareis a first guess based on the observed materialexposed at the sample surface. Users arereminded that laser ablation is an inherentlythree dimensional analytical technique andthat, especially in geological specimens, thematerial type can change substantially over avery short distance. As such, users areencouraged to review the measured signals forall ablations. Software such as LADR makes ittrivial for the user to assign differentquantification routines to different integrationperiods.

The workflow outlined in this document is fullysupported by GeoStar v10.06, LADR v1.1.01,Agilent Mass Hunter, Analytic Jena Aspect MS,and Thermo Qtegra.

www.norsci.com/geostar/www.norsci.com/ladr/

Support will be expanded to other softwarepackages as instrument manufacturers anddevelopers adopt this exciting new workflow.

GeoStar and LADR are trademarks of Norris Scientific. All othertrademarks are the property of their respective owners and areonly used in a descriptive capacity.

Application Note NSAP19A12019 © Norris Scientific PTY LTD


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