I have used the Olympus DELTA, which gave accurate results for a range of materials. Our unit came with several material-specific settings (soils, alloys, mining etc), so one instrument is capable of analysing more than one type of material. I do believe, however, that a factory upgrade is needed for adding and/or removing specific elements from analytic settings- or you can, of course, specify which elements you require when you order a unit. We did have some overheating issues with our DELTA that were never completely resolved. This may have been specific to our particular unit, though, and (I would hope) not typical of Olympus instruments.

We recently changed to a Bruker Tracer III-SD. In terms of accuracy and precision, it is similar (or possibly a little better) than the DELTA. The included software is, however, significantly more flexible. There is much more user-adjustment available (voltage and current settings, and filter choices) and the calibration software allows you to choose whichever elements you want for you analyses. We routinely run the Bruker for several hours with no suggestion of overheating. Bruker's literature and online support is also excellent. Without sounding like an advertisement (I have no commercial affiliation with Bruker), I would suggest that you also consider one of their instruments, if possible.

I haven't used a Niton, so cannot comment on them.

We mainly analyze archaeological stone tools- basalts, obsidians, etc.

Dear @Dan,

If you want a versatile one with flexibility and wider range of heavy metal coverage (practically), with better detection limits for your main applications, you can go for the polarized /Cartesian geometry secondary excitation EDXRF from PanAlytical, SpectroXEPOS or Rigaku (I don't remember the name). They have detector ( Drift detectors...Peltier cooled..no liq N2 required), source and secondary target combinations according to your needs. You can first decide on the elements of your interest and the detection-limits. I think the most sensitive of them all is the Panalytical Epsilon-5 .(because I worked on it of course :)). But this has Ge detector with liq N2 cooling. They also have a Epsilon-3 now with SDD peltier cooled detectors. It depends on your budget , application, & detection limit requirements, which one you would prefer. Spectro-XEPOS has a good quantification software (turboquant).

I could not tell you about the 2 products you mentioned. If you have already decided that you will buy one of these I am sorry for bothering you.

Regarding accuracy...the instrument provider can only give you the guarantee of precision or good reproducibility., but accuracy depends on the analyst and how well he/she calibrates.

Dear Dan,

Have you considered Oxford Instruments? We too supply a range of HHXRF and benchtop EDXRF analysers that can be configured for multiple applications and have very competitive precision and accuracy . Take a look at our website and if you have any questions please do not hesitate to get back to me via this site.

http://www.oxford-instruments.com/products/analysers/handheld-xrf-analyser-x-met7000-series

Dear Dan,

You could also request the vendor to analyze some known samples similar to your requirements (or Certified reference materials) without mentioning their name and check the precision and accuracy, along with time taken for analysis (throughput), X-ray spectra quality etc. I think this is the best way you could judge the performance parameters. But of course it depends on whether the vendor agrees to do so.

Dear Dan,

take a look also here:

http://www.xglab.it/compact-portable-xrf-spectrometer-elio.shtml

If you have decided to go for Portable (hand-held) EDXRF then I think Niton (Thermo-Scientific) has very good reputation behind them for this variety. I think it also has the flexibility to be used as a bench-top EDXRF with properly homogenized samples.

However, you could check the local after sales service record before buying it. usually the commercial instruments durability and usability depends on local service..and I suppose Thermo-scientific has a good service network.

You might also consider Ampterk's XRF kit. But it seems that nilton's EDXRF kit is more user friendly.

http://www.amptek.com/xrfkit.html

Dear Dan,

You may have something close to your answer in the following article link:

http://onlinelibrary.wiley.com/doi/10.1002/xrs.2485/pdf.

(wileyonlinelibrary.com) DOI 10.1002/xrs.2485

Applicability of portable XRF systems for screening waste loads on hazardous substances as incoming inspection at waste handling plants

C. Vanhoof, * K. A. Holschbach-Bussian, B. M. Bussian, R. Clevend and K. Furtmanne

7 portable commercial EDXRF has been compared here...including Thermo Niton XL3t GOLDD

If you don't have access to X-ray Spectrometry journal you may write to the authors.