17June2015

XRF Meeting Report 17^th June 2015

A joint BCA/ RSC Atomic Spectroscopy Group Meeting at University of Leicester.

A PDF version (269 kb) of this report (Frep15.pdf) can be downloaded from the foot of this page. Clicking the file name will load the file into your browser, clicking the small blue down arrow to the far right of the file name will download a copy to your computer.

Overview of Event

The XRF group is a sub-committee of the British Crystallographic Association (BCA) which covers a range of instrument techniques and interest areas. Further details can be found at http://www.crystallography.org.uk/

Annual meetings are held by each sub-committee which gathers together industrial users, academics and instrument vendors in one place. This year’s XRF meeting was held at the University of Leicester in collaboration with the Royal Society of Chemistry and gathered together 57 delegates along with 12 vendor stands presenting their products.

Summary of the Morning Session:

Arriving in the beautiful surroundings of Victoria Park backing onto De Montfort Hall it is pleasant for the XRF user to arrive at this one day event which gathers together the XRF community from academics to industry users and of course instrument and sample preparation vendors.

As an industrial XRF user I relish the chance to escape the lab albeit for one day to discuss my current XRF issues with likeminded individuals and hear of their experiences and challenges that are so similar yet from a completely different world. The outside and a telephone free environment to do this is such a rarity.

The day did not disappoint in this respect. From the moment I arrived and signed in, the usual faces greeted me and the ‘challenging’ conversations ensued. Along with meeting new XRF users and interested parties it really is a good mix for thought provoking ideas.

The formal talks began as follows with a good mix of breaks to continue these thoughts and ideas.

Morning Session.

Morning Speakers: left to right Dave Taylor(Chair) Heather Harrison, Peter Webb, Neil Eatherington, David Beveridge, Ros Schwarz (Chair) and David Maclachlan.

Neil Etherington, PANalytical Ltd, Environmental Science Centre (formally British Geological Survey whom PANalytical have recently acquired after closing their Cambridge demo labs in the UK) gave a talk on combining EDXRF and WDXRF to optimise the analysis of a range of element in soils and sediments.

This was a very relevant talk to all XRF users at choosing your instruments to their strengths and made me think more about the use of the instruments at my disposal.

Specifically, Neil centred on As and Sn mapping in SW England utilising the Zetium (WDXRF) and ProTrace package from PANalytical to deliver 41 trace elements in one application and a measurement time of ~50 minutes.

ED(P)XRF (polarised ED) was then presented using the Epsilon 5 to deliver low level analysis on elements that proved problematic for the Rh tube of the WDXRF. The combined problem of tube target combined with the fact that the high energy K-lines can now be selected on the Epsilon 5 delivered better LLD’s for these elements using a 2 target, 17 minute analysis. Interestingly the new PANalytical WDXRF (Zetium which replaces the Axios) can be configured with an EDXRF channelset.

Peter Webb, Open University delivered a thought provoking talk on reporting XRF results at concentrations approaching the detection limit. This talk was dedicated to John S Watson who was a familiar face within the XRF community and recently passed away.

Running the GeoPT scheme which has so far delivered 37 rounds of proficiency testing on more than 40 samples delivers some very useful data to interrogate.

Elements showing poor fit to the consensus (As, Sb, W, Cd, Mo) were looked into further and a breakdown by instrument technique were presented. ICP-MS was used alongside EDXRF and WDXRF along with other techniques and the data was of interest to all. Further discussions later in the day and between delegates brought up the idea that manufacturer presented detection limits could be considered by some as lower reporting limits and further education of XRF users could be beneficial to calculate lower limits of quantification and the associated uncertainty of measurement close to the detection limit.

Exhibition session

From sample preparation to fusion and pellet production to analysis with handheld (including a LIBS handheld from Oxford Instruments) across to benchtop ED and full WDXRF was on all show. A first look at all the exhibitors as well as the vital discussions between delegates was then followed by a further two talks.

David Maclachlan, Johnson Matthey presented a summary of JM divisions and then an interesting insight into the world of catalyst analysis. From the researcher who has limited sample but wants to know everything about the sample, XRF provides an essential part in this. The challenges that also arise from analysis taking place across multiple techniques, and sites proved that the environment plays a large part to analytical accuracy and the associated measurement uncertainty.

The results from DOT-2 - David Beveridge presented the results from DOT-2, the sample that delegates were provided with last year. This meeting is a good arena for trialling samples of types that delegates are not used to, but this sample was so unfamiliar that only 3 sets of results were presented. Link to the presentation…. Heather Harrison from British Gypsum provided this year’s sample, DOT-3, which should prove more popular. I have challenged my XRF trainee to provide her best analytical results by thinking through all aspects of material identification and analysis and hopefully all the well spent training will make me a very proud mentor.

In between talks the time is spent digesting the information in a work/hassle free environment and the nature of the day makes the bouncing of these ideas across many different minds a very useful event indeed.

Judith Bain, Alfred H Knight International Ltd

Afternoon Session.

Afternoon Speakers: left to right Frederic Davidts, Nick Marsh (local organiser), Ade Band, Raphael Yerly, David Beveridge and Heather Harrison (Chairs) and Rainer Schramm.

After lunch, Raphael Yerly from Thermo Scientific gave a talk on a new application of WD-XRF, analysing small samples, or small areas of larger inhomogeneous samples, using an internal mask to restrict the take-off beam. He first showed that it is possible to get good quantitative results from 0.5 mm diameter fused beads made with as little as 0.05g of sample. Raphael then discussed the analysis of inhomogeneous samples, moved on a slider across the internal mask to pick out different regions, exemplified by point analysis on a defect in stainless steel. He illustrated the mapping capability with examples from a weld between two different steels and a limestone with a dolomite vein, adding the usual caveat that mapping takes a long time, and that a line scan can give much of the same information. He finished by showing us some more examples of the versatility of the technique.

Next, Rainer Schramm from FLUXANA introduced his company’s new electrical fusion system and gave us some examples of its use. He showed us very good results from oxidic materials and then discussed more difficult materials such as ferroalloys. Ferroalloys, which must be oxidised before fusion, can either be placed with the vanadium pentoxide oxidant on top of the flux in one step, or oxidised first and then the flux added in a two step procedure. Adding tungstic oxide as an internal standard for silicon in ferrosilicon gave impressive precision. Lids on the crucibles retain splashed material and a quartz window is available so that the melting can be observed without contamination of the furnace, particularly during method development. Lastly, Rainer talked about the analysis of continuous casting powders that can contain up to 20% carbon which must be burnt off and which require fluorine analysis. Because the furnace is small and closed, loss of fluorine (and other volatiles such as chlorine and sulphur) is controlled and good results can be obtained.

After a break for a welcome cup of tea, Frederic Davidts from SOCACHIM gave a comprehensive discussion of the care of platinumware. He pointed out the advantages of using platinum including its high melting point, high strength and resistance to corrosion at fusion temperatures, and its good formability and outlined the different alloys. He suggested some basic precautions such as using platinum-tipped tongs, clean refractories and oxidising furnace conditions, showing some dramatic pictures of what happens when things go wrong. Elements including Sb, As, P, Se and Te (and their compounds) poison platinum and must be avoided; the more common troublemakers, including sulphides, metal powders, ferroalloys and silicon carbide must be fully oxidised or they will not dissolve properly in flux and will damage the platinum. Frederic showed some data to illustrate the importance of a flat casting dish (mould) and discussed the best technique for polishing. He outlined the acids used for cleaning platinumware, such as boiling dilute HCl or 20% w/v citric acid in an ultrasonic bath. Finally, he pointed out that if you have to spend a long time on cleaning and polishing or you suspect that problems with the flatness of your beads is beginning to affect your results, then that is the time to trade in for new labware. And, of course, it is fully recyclable!

For the last talk of the day, we had a reminder of the uses of our technique. Adrian Band from the University of Leicester described his PhD research on tracing the history in deep time back to the Early Palaeozoic of the re-arrangements of the ocean basins, using the different chemical domains of the depleted mantle that erupts to give mid-ocean ridge basalts (MORB). However, it is very important that these ancient rocks are unmodified by subsequent geological events such as subduction, obduction or weathering. After setting the scene by showing what these rocks, known as ophiolites, look like and where they are found, he described screening his MORB material, looking at the behaviour of the ratios of elements determined by XRF and of each element to the rock to loss on ignition of the material. Detailed ICP-MS work at levels below the range of XRF and finally isotope analysis gave data that Adrian used as new evidence for widespread and early Indian-type MORB with a possible shallow origin.

The meeting finished with a question and answer session which included a discussion of the results that Peter Webb presented earlier in the day and answered several questions from the audience.

Ros Schwarz

....and finaly some scenes from the Exhibition