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XRF can be used for applications where elemental analysis is needed for elements Mg and heavier. This does not only include heavy metals. The following table shows what elements are measurable by XRF. View PDF of it here.
Consumer Products testing is only one of many applications for handheld XRF. We have well-developed mining and geochemical applications for XRF, for a large number of elements. Please have a look at our website for information on XRF in mining and geochemistry:
http://www.olympus-ims.com/en/innovx-xrf-xrd/geochemistry/
http://www.olympus-ims.com/en/xrf-xrd/delta-handheld/delta-mining/
XRF can be used for testing of Rare Earth Elements (REE). We recommend using a 50kV capable analyzer for this application, such as the Delta-50 or X-5000, since detection limits and performance on a few key REE (La, Ce, Pr, Nd) will be vastly improved.
XRF cannot test directly for Li in any sample. If some aluminum alloy grade can be uniquely identified by other elements (e.g. Fe, Cu, Zn), our Alloy Mode software can identify that grade and notify the user that this grade also contains Li. But the XRF cannot test directly for Li.
For light plastics or light organic materials, penetration is on the order of mm or cm. For heavier plastics (like PVC), or plastics with metallic additives (like Ti, Zn), or aluminum alloys, penetration is on the order of a few mm. For heavier metal alloys (Ti, Fe, etc) penetration is on the order of 100s of um, and for the heaviest metals (gold, lead, etc) penetration is a few 10s of um.
Testing through a surface layer, whether it be corrosion, contamination, paint, or an anodized surface, depends on what is in the surface layer, how thick it is, and what elements are being tested in the substrate layer. It is always preferable to clean off a surface coating and test bare substrate. Surface coatings can partially or completely shield the substrate elements, and this is especially true for lighter elements like Mg and Al. If the surface coating is thin and the substrate elements are heavier (e.g. Pb, Sn, etc) then testing through the coating may be possible, though a user should validate that this is possible. Again, for best results it is always better to test a clean and uncoated homogeneous sample.
It is possible to produce correlation between wet chemistry and XRF results. The correlation works best when you are dealing with homogeneous materials. For materials where the sample type matches the calibration on the XRF instrument, correlation is usually good, 30% or better (that is where the IEC document chooses 30% as a broad buffer zone around screening levels). Where material types don't exactly match the calibration, any bias in results between XRF and wet chemistry can be corrected by an adjustment to the calibration. So, for example, if you see good correlation with wet chemistry results but a bias of 20% high in XRF results, you can adjust the XRF calibration to get results to match the independent tests.
XRF can be used to test liquids or food products, including juice concentrate. However, whether XRF will be useful depends on what you are looking for. If it's a food safety application looking for heavy metals (e.g., Pb, Hg) the control level is usually below the detection limit of the analyzer. XRF has detection limits in the ppm range, but heavy metals limits for food are usually ppb or lower. So you can detect high levels of contamination, but you cannot certify that food is safe for consumption based on heavy metal content.
If the application is for looking at nutrient content in foods or soils, XRF may be able to help. XRF can detect P and Ca in foods, at detection limits of a few 100ppm for P and ~50ppm for Ca.
As long as an XRF instrument is properly used, x-ray exposure to the user is no higher than (or comparable to) exposure from background radiation that we encounter in daily activities. Handheld analyzers have a number of features to ensure safe use; for example, there is a sensor to prevent the user from pointing the analyzer into the air and running a test with no sample present. But appropriate safety measures should be taken: for example, do not put your hands or any body part near the analysis window during a test.
Certification requirements vary based on location. Please contact our local sales staff in your area to explain specific requirements for your state/province/country.
XRF can be used to test ceramics, as long as you are looking for metals within the detection limits. Detection limits for ceramics will be similar to those for soil samples (the matrix types are similar from an x-ray perspective) and you can find information on Soil detection limits on our website:
http://www.olympus-ims.com/en/xrf-xrd/delta-handheld/delta-env/
Handheld XRF can be used to produce a map of elements on a surface, but you would need to use some 3rd party software package to produce an image. The XRF beam spot size is 10mm, and can be collimated down to 3mm, so you wouldn't get any better spatial resolution than that. You won't be able to produce a map of a smaller surface with the resolution of a SEM.
When Handheld XRF is used to produce an element map of a surface, it is usually for some large area outdoors, e.g. environmental site remediation or geochemical characterization.
LOD is the lowest concentration of a substance that the analyzer can reliably detect. LODs are defined for homogeneous materials, with low interference from other elements - basically, ideal samples. LODs can vary based on different sample types and conditions. We have more information about detection limits for different applications on our website:
Environmental Analysis
Consumer Product Analysis
XRF can be used to test almost any sample type - if you can place it in front of the analyzer window, you can analyze it by XRF. The aim is to define what you are testing for in the sample. It needs to be an element (Mg or heavier) and needs to be present in ppm levels or higher. You also need to confirm that the detection limit can be reached for that sample type, since they vary based on material.
Information on elements testable by XRF is on our website here.
XRF can test for elemental silicon (Si) in plastic samples, and the detection limits would be, very approximately, ~0.1% in the best case. Fluorine (F) cannot be tested by handheld XRF.
For painted or coated aluminum alloys, it is usually preferred or required to remove the surface coating and test the uncoated substrate. Since aluminum is a light metal, the x-rays that it produces are weak and easily absorbed by a surface coating. It is usually not possible to identify an aluminum alloy grade through a coating. Certain heavier elements in the alloy (e.g. lead, tin) may be able to be identified through a coating, but the coating will likely interfere with measurement.
X-ray penetration depth depends on sample material. For light plastics or light organic materials, penetration is on the order of mm or cm. For heavier plastics (like PVC), or plastics with metallic additives (like Ti, Zn), or aluminum alloys, penetration is on the order of a few mm. For heavier metal alloys (Ti, Fe, etc) penetration is on the order of 100s of um, and for the heaviest metals (gold, lead, etc) penetration is a few 10s of um.
Be aware that if your sample is thinner than the penetration depth, elements in a support or anything behind the sample may be visible in the XRF spectrum. The best option for sample support is to test the sample with the analyzer pointing up and the sample resting on the analyzer window, so no support is needed. Olympus Innov-X offers shielded test stands to allow users to test like this, which is especially useful for testing smaller components or samples.
Yes, XRF can be used to test both metal alloys and hydraulic fluids. The most common metals applications are alloy grade matching (determining an alloy's grade based on measured chemical content) and chemistry analysis looking for certain metals in an alloy.
Hydraulic fluids can be tested for wear metals, as well as certain lighter elements like P, S, and Cl. You can find more information on our website about Alloy testing
XRF is useful in the automotive industry for metals identification, as well as in support of environmental compliance for regulations such as the EU End of Life Vehicles (ELV) directive, which is similar to RoHS in target restricted substances (lead, cadmium, etc.). You can find more information about following topics through the links below:
Metals identification
XRF information on restricted substances (includingELV)
Information from the European Commission on ELV
Testing of aluminum alloys is usually done with 1 or 2 exposure settings, a high voltage (25-40kV) and a lower voltage (~10kV). The lower voltage is what tests specifically for aluminum content. The handheld instrument can be used safely at these settings, but of course, users should always follow appropriate safety measures. Olympus Innov-X sales representatives will do safety training as part of product delivery and installation.
XRF can be used in many industrial applications. If you are testing bearings, you can test either for restricted elements (like other consumer products) or for alloy chemistry composition or grade identification. We have more information about alloy grade identification on our website and restricted elements testing.
To get best results with XRF, it is always preferable to test homogeneous materials. The calibration is normally based on other homogeneous materials, and that's what the analyzer software is expecting. So we recommend that XRF testing be focused on raw materials or disassembled components as much as possible.
That said, XRF is commonly used to test inhomogeneous electronics components. As one example, handheld XRF analyzers usually offer small spot collimation to concentrate analysis on one area of interest. This could be used to restrict testing to a solder joint on a printer circuit board (PCB) so that x-rays from the analyzer are mostly or only testing the solder material.
Another common way that inhomogeneous electronics components are tested is using qualitative screening. Say, for example, you are manufacturing a surface mount component, and a leaded solder was used instead of lead-free solder. Handheld XRF may not be able to give a precise Pb content for the solder only, since the Pb signal will be diluted by all other materials present. However, if XRF is likely to detect Pb in the sample, it may not matter whether Pb is detected at 40% or 4% or 0.4% - if the Pb reading is well above what is seen on components made with lead-free solder, then a potential failure has been identified and the manufacturer should conduct follow-up tests. Follow-up could include removing solder from the component (if possible) and testing it separately, testing the same solder batch pre-fabrication, and confirmation by lab analysis of the solder material tested separately.
The Delta XRF spot size is ~10mm in diameter, so an analysis area of ~0.8cm2. A small spot collimator is available with spot size of 3mm, for ~0.07cm2. Please note that when using small spot collimation, detection limits are usually higher than larger spots, since you are testing a smaller area and getting less information about your sample.
There are 2 kinds of inconclusive readings from XRF:
1) XRF result is too close to the screening level. For example, Pb = 900ppm when the action level is 1000ppm and the screening levels have been set to 700ppm (Pass) and 1300ppm (Fail).
2) XRF result gives a high level of some element that is restricted only in some chemical form. For example, Br = 5000ppm, where the action level for Br is 300ppm but the restricted compounds are certain flame retardants that contain Br, not Br itself. XRF can tell you how much Br is present, but not what chemical form it is in or what molecule it is bound to.
The "inconclusive" range in (1) depends on what sort of buffer zone the user wants to set up around the screening levels. IEC 62321 recommends, broadly, a +/- 30% range for homogeneous materials and +/- 50% for composite materials. It is up to the user to decide how large the inconclusive range should be to ensure that correct decisions are made about what samples need no further testing, which samples are deemed failures that require corrective action, and which samples need more testing to determine "Pass" or "Fail" status.
This is a sample scheme of what XRF screening levels might look like for a user doing RoHS screening by XRF, taken from the IEC 62321 Guideline. Taking lead (Pb) for example, the recommended screening guideline around the action level is +/- 30% + 3-sigma. So for a Pass, the XRF result needs to be less than 700 - 3*sigma, and for a Fail, the XRF result would be 1300 + 3*sigma. "Sigma" is the instrument uncertainty, which is calculated for each reading and is normally shown for the user along with the reading.
The "inconclusive" range (e.g. 700 - 3*sigma to 1300 + 3*sigma) depends on what sort of buffer zone the user wants to set up around the screening levels. It is up to the user to decide how large the inconclusive range should be to ensure that correct decisions are made about what samples need no further testing, which samples are deemed failures that require corrective action, and which samples need more testing to determine "Pass" or "Fail" status.
Thank you for your interest in Olympus Innov-X XRF analyzers. Please contact our sales team for specific information on pricing, as this varies by model and application.
The choice of x-ray tube maximum voltage will not have much of an effect on alloy testing where steels are the main sample type. The difference in maximum tube voltage (40/45/50kV) mainly has an impact on trace level detection limits for certain elements like silver (Ag), cadmium (Cd), tin (Sn), antimony (Sb), and a handful of other elements that rarely appear in alloy testing. The maximum tube voltage spec mainly has an impact for consumer products testing, environmental, and mining applications, but rarely is a factor in alloy testing. In practice, most alloy tests run at voltages of 40kV or lower - this is determined by the manufacturer, but there is usually little benefit to having an x-ray tube that can run any higher than 40kV.
Temperature of sample will not normally affect XRF results. Handheld XRF analyzers will have some ambient temperature operating range, e.g. -10 - 50C. There are applications developed where handheld XRF can test samples well outside of this temperature range. For example, handheld XRF can be used to test in-service pipes at petrochemical plants where the metal surface temperature is as high as 800F. Tests must of course be short, and other precautions need to be taken to protect the analyzer. But testing of very hot or very cold samples will not affect results.
The level of sample preparation for XRF testing will vary based on what kind of testing is being done and what the elements of interest are, but for the situation described where the surface has oil that may contain heavy metals, it would be strongly preferred to clean the surface before testing. Any elements (e.g. lead) in the oil layer would show up in results, though their contribution to the final result depends on how much of the element is present and how thick the layer is. Even if the oil layer contains elements that are not of interest in the substrate, there is a risk that the oil layer can shield the substrate and cause lower readings for substrate elements.
Also, with oil coatings, there is the risk that the window of the XRF analyzer can become contaminated. The window can be cleaned and/or changed, but it is best to avoid contamination as much as possible.
Sampling Plans should always be used in conjunction with doing a material and supplier risk assessment. If there is any risk high or medium, the material should be sampled. A Mil-STD-105D normal sampling size can be used as a sampling plan.
This is an excellent method to use when implementing a reasonable test program. If possible, the material should be screened before leaving a supplier's facility.
Intertek provides training throughout the world to implement reasonable test program's as well as proper operation training for handheld XRF.
You can screen electronic equipment to see if a substance is present, but the components must be in a homogeneous form for conclusive results.