In the past, metal fabricators and quality control personnel were required to perform costly, time-consuming laboratory tests in order to verify materials. Progress in technology for elemental analysis has enabled users to obtain laboratory-grade results in the field, practically instantly.
Often, the greatest challenge can be selecting the correct technology for your application. Present day elemental analysis techniques include handheld X-ray fluorescence (XRF), handheld laser induced breakdown spectroscopy (LIBS), and optical emission spectroscopy (OES). Insight into how these technologies compare to each other is vital so that it is possible to select the best option for a business with confidence.
How XRF, LIBS and OES work
XRF, LIBS, and OES are various kinds of elemental analysis techniques. Each works in its own distinct way to supply results (with different advantages and disadvantages). Users may select one technology over the other for multiple reasons. The following explains how each technology works.
XRF is a non-destructive analytical technique used to discern the elemental composition of materials. During the XRF process, a sample is irradiated with high energy X-rays produced by an XRF analyzer. This leads the atoms in the sample to emit secondary (or fluorescent) X-rays which can be detected and processed to discover which element is present. Each fluorescent X-ray is individual to the elemental composition of the sample, which makes it a brilliant tool for qualitative and quantitative analysis.
Another analytical technique, LIBS, can be used to determine elemental chemistry. During the LIBS process a high-focused laser ablates the surface of a sample. A plasma is formed that consists of electronically excited atoms and ions. As these atoms decay back into their ground states, they emit “unique fingerprints” or characteristic wavelengths of light. Each element’s “fingerprints” are distinctive. Like XRF, LIBS is an brilliant tool for conducting qualitative and quantitative analysis.
OES is the third technique utilized to obtain elemental chemistry. It is like LIBS, but instead employs a high voltage electrical pulse to excite atoms. Each atom in the arc/spark discharge formed at the surface of the sample emits specific lines that are selectively detected by an optical spectrometer in the OES device. The features of the lines are used to establish the chemical composition of the sample being tested.
Choosing the Right Technology for Your Application
There are numerous important features to think about before settling on a technology solution for a business. The key factors to review are outlined in the following:
Analytical Range
Handheld XRF and LIBS are best considered as complementary technologies. Users can combine them to cover a broader range of elements – including light elements (such as carbon), which a few high-end LIBS analyzers can now detect. Handheld XRF can usually detect Magnesium (Mg) through Uranium (U). The analytical range of portable LIBS analyzers is a bit more dispersed when regarding the periodic table, but may include elements such as Aluminum (Al), Carbon (C), Titanium (Ti), Silicon (Si), Vanadium (V), Chromium (Cr), Iron (Fe), Manganese (Mn), Nickel (Ni), Cobalt (Co), Copper (Cu), Molybdenum (Mo), Niobium (Nb), and Tungsten (W) – making it the perfect solution for metals industries. The elements and concentrations that can be determined by OES analyzers vary in regard to the material being tested and the kind of analyzer used. However, the typical analytical range is from Carbon (C) – Tungsten (W).
Portability
It is easy to transport handheld XRF and LIBS analyzers due to their lightweight design and compact formfactor. In fact, today’s most advanced handheld XRF and LIBS analyzers can be used directly on the manufacturing line and weigh less than seven pounds. For operators that require access to tight or hard-to-reach spaces, portable XRF and LIBS analyzers travel with the operator safely and conveniently.
In contrast, mobile OES can be harder to deploy because of its weight, limited range of access and bulky cart configuration. OES devices can weigh more than 90 pounds once the bulk argon tank required for operation is accounted for. In addition, analysis is conducted through a pistol grip device connected to the OES cart by a hose. Due to this, users can only travel as far as the hose will take them before first moving the OES cart.
Time
Today's most advanced handheld XRF and LIBS analyzers can produce results in less than 10 seconds, in comparison with around 15 seconds on mobile OES. Although the time differential may appear insignificant, it can easily mount up if numerous readings are needed throughout the day. Portable LIBS and mobile OES also need more steps before it is possible to conduct analysis. In order to ensure optimal analysis, those steps include daily set-up procedures and sample preparation. These setup procedures can take just 10 minutes on LIBS and as much as 30 minutes on mobile OES. Handheld XRF does not need daily maintenance and is best described as “point and shoot” due to the ease associated with use.
Sample Surface
As previously mentioned, handheld XRF is a non-destructive method of conducting elemental analysis. Portable LIBS and mobile OES are thought of as minimally destructive for two reasons. The first being that sample preparation is required before conducting analysis. Sample preparation is achieved by grinding the sample to eliminate surface impurities. The second reason why LIBS and OES are thought of as minimally destructive is that a small burn mark remains on the sample where the laser/ electrical pulse occurs.
Using LIBS Technology to Detect Carbon
LIBS has been a long established analytical technique used for material verification. It is only in recent times that companies such as Thermo Fisher Scientific have managed to unlock the use of the technology to measure carbon. The new Thermo Scientific Niton Apollo handheld LIBS analyzer weighs 6.4 pounds and can quantify carbon concentrations in low alloy and L+H grade stainless steels, as well as calculating carbon equivalency.
Gaining the ability to measure carbon will prove to be valuable for quality control departments, petrochemical plants, metal fabricators, and scrap recyclers who seek to measure low concentrations of carbon in metal quickly, directly on the line, and under conditions where previous technologies were too cumbersome.
What’s Next for Elemental Analysis Technology?
Various kinds of elemental analyzers are now available to help metal fabricators and manufacturers perform laboratory-grade analysis within seconds under a variety of conditions in the field. In the future, analyzer options are expected to grow even further as engineers and researchers continue to miniaturize the technology so that it can be integrated directly into manufacturing processes, or perhaps someday even carried by drones, to be utilized effectively wherever elemental analysis is required.
It is key for manufacturers of elemental analysis technology to respond to changes in the needs and preferences of the marketplace. Thermo Fisher Scientific works in close partnership with metal fabricators and quality control personnel to ensure maximum value. For instance: In the last few years, the company’s XRF and LIBS analyzers have become so simple to use and mobile that they can be used for fast, dependable elemental identification and material verification in almost all field environments, locations or weather conditions.
Acknowledgments
Produced from materials originally authored by Brian Dalton, Product Manager from Thermo Fisher Scientific.
This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific – Handheld Elemental & Radiation Detection.
For more information on this source, please visit Thermo Fisher Scientific – Handheld Elemental & Radiation Detection.