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Recent years have seen considerable advancements in XRF and LIBS analyzers - they have become viable for fast and reliable elemental identification and material verification thanks to their ease of use and convenience. Today, the analyzers are efficiently used in almost any location, environment, or weather condition, but, in spite of their advantages, the biggest challenge now can be choosing the right technology for your application.
Selecting the right technology presents a challenge
Previously, material verification was conducted by laboratory tests that required a heavy investment of time, labor, and money. Now, significant advances have been made in this field, and users can get laboratory-grade results almost immediately, on-site. However, it can be challenging to know which technology applies to each application.
Handheld laser-induced breakdown spectroscopy (LIBS), optical emission spectroscopy (OES), and X-ray fluorescence (XRF) represent a variety of elemental analysis techniques that are currently available. The key to fully gaining the advantages of these techniques lies within understanding how they compare against one another.
Comparing XRF, LIBS, and OES
Each type of elemental analysis comes with specific pros and cons. Understanding how each technology works is the first key step to being able to select the right technique for a given application confidently.
LIBS is used to uncover the elemental composition of a sample. A high-focused laser ablates the surface of a sample, which creates a plasma full of electronically excited atoms and ions. During the process of decaying back to their ground states, these atoms and ions emit wavelengths of light that are characteristic of the elements present in the sample.
OES obtains the elemental chemistry of a sample by exciting atoms with a high voltage electrical pulse, which causes a discharge at the surface of the sample where the atoms emit lines that are then selectively detected by an optical spectrometer. These lines determine the elements that exist in a sample.
XRF is a nondestructive analytical technique also used for identifying the elemental composition of a selected material. The method involves using high energy X-rays to irradiate a sample, initiating the emission of secondary X-rays from the material’s atoms. These are analyzed to determine the elements present in the sample.
Choosing which technology is suitable
Before deciding on a technology to use, there are a few key factors to be considered. The first is the analytical range of the technique. Often, XRF and LIBS are used as complementary technologies, used alongside each other to extend the range of elements that can be detected.
XRF can usually detect elements from magnesium to uranium, whereas the LIBS range tends to be more scattered through the period table, mostly covering the elements of carbon, aluminum, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, niobium, molybdenum, and tungsten. OES, on the other hand, can detect a different range of elements depending on the material being sampled, although its usual range sits between carbon and tungsten.
The second consideration is portability. While XRF and LIBS are handheld and lightweight, and therefore can be easily transported, mobile OES can be more difficult to transport because it is heavier and bulkier.
Testing time is another key consideration. The best XRF and LIBS analyzers can produce results in less than 10 seconds. OES is slightly slower, producing results in around 15 seconds. While this difference seems negligible, if numerous analyses are required to be conducted in a day, the 5-second difference can accumulate to a significant amount of time. What’s more, LIBS and OES also require extra steps to be taken before analysis, adding to the time spent in conducting tests. For LIBS, set-up time is around 10 minutes, and for OES, it can be around half an hour.
Finally, sample surfaces are to be considered. The XRF method is nondestructive, but LIBS and OES are minimally destructive due to the sample preparation that is required, which involves grinding the sample to remove surface impurities.
The future for elemental analysis technology
It is expected that even more elemental analyzers will be available in the future, making on the spot, instant analysis of elemental compositions easy and accessible. The key to capitalizing on these new technologies will be in understanding how each technology works along with its pros and cons to enable the selection of the most suitable device for the job.
Further Reading
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