Sample preparation is the key to quality analysis with a laser analyser
Sample preparation is the most important step of any chemical analysis. To get the best results with any elemental alloy analyser regardless of the technology, the sample must be clean before taking a measurement. Otherwise the results are always compromised at least to some extent. The effect of dirty surfaces will vary and some technologies are more forgiving to sample surface conditions than others.
How well an analyser can tolerate dirty surfaces depends on many variables such as the nature of physical phenomenon behind the technology, analysis spot size, the penetration depth of the excitation and type of the contamination on the sample surface.
Elemental alloy analysis is usually carried out by using either OES (optical emission spectroscopy), XRF (X-ray fluorescence) or with LIBS (laser induced breakdown spectroscopy). Each technology is different and so is the amount of sample preparation needed. Where XRF can tolerate even quite dirty surfaces, to get quality results with spark OES, proper sample preparation is always required. LIBS technology falls in between the two.
LIBS is a surface analysis technique, so the penetration of the laser beam is typically just couple of microns deep. This means that the sample surface must be relatively clean to get accurate and precise results.
Typically when measuring stainless steels or titanium, magnesium, aluminium or nickel alloys, no sample preparation is needed as these sample types doesn’t form clear patina or thick oxide layer on the sample surface. Often even anodised aluminium samples can be measured directly with no sample preparation. If the sample is dusty or has water, oil or cutting fluid on the surface it’s always good practice to wipe it clean with a piece of cloth or something similar.
For low alloyed steels, manganese steels and copper based alloys it’s different. Thick rust or heavy patina affects the analysis results significantly and must be removed prior to taking an analysis, especially with a laser analyser. Also any paint, lacquer or coating is too thick to be burned through with the laser. Sometimes the coatings can be tricky to spot. As an example, alloy wheels are always covered with a rather thick protective layer of lacquer, which must be ground away an analysis. Otherwise the results cannot be trusted.
Choosing the right sample preparation tools
There’s a huge variety of sample preparation tools to choose from; small multi tools to heavy duty angle grinders. Here are our top three tips to keep in mind when choosing a suitable tool.
1) When operating the instrument at a scrap yard, the sample preparation tools should be cordless. Therefore an angle grinder with powerful 18V lithium ion battery is often the most recommended choice. Smaller multi tools are convenient to use and even fit in the pocket but might sometimes lack power when dealing with large number of samples.
2) Choosing the right grinding material makes a huge difference because there will always be some grinding material residue left on the sample surface and some materials cause more issues with the analysis than others. The recommended grinding material is aluminium oxide (Al2O3).
3) When using an aluminium oxide grinding discs or sand paper, the effect on the analysis result is minimal, but still it is a good idea to wipe the dust away from the surface before taking an analysis. Grinding tools made of zirconium oxide, tungsten carbide or silicon should not be used as those might compromise the results.
Hitachi High-Tech’s Vulcan handheld laser analyser is one of the fastest metals analysers on the market; just pull the trigger and your results will show in one second. It’s also one of the lightest and the easiest to use. Vulcan’s simple user interface significantly reduces user error, delivering far more accurate and consistent results.
Want to find out more? Visit vulcan.oxford-instruments.com, talk to our experts or book a demo.
Air and water quality are increasingly important concerns for the shipping and boating industries. The International Maritime Organization (IMO) is implementing new regulations regarding sulfur content in marine fuels. X-ray fluorescence (XRF) analysers provide one of the most cost-effective techniques for measuring sulfur content both at the laboratory or on-board a ship.
IMO’s new global low sulfur fuel oil requirement
As part of ongoing efforts to reduce air pollution released from burning fossil fuels, the IMO has announced that the Maritime Protection Committee (MEPC) agreed to implement the proposed 0.50% global sulfur cap on marine fuels on 1 January 2020.
This is a significant reduction from the current limit of 3.50% which has been in place since 2012.
Within sulfur emission control areas (ECA), the sulfur limit remains at the 0.10% level established in 2015. ECAs are established in the Baltic Sea area, North Sea area, North American area, United States Caribbean Sea area and three regions in China – the Pearl River Delta, Yangtze River Delta and Bohai Sea Region.
To ensure compliance, a variety of control measures can be put in place, such as on-board sulfur testing .
Using X-ray fluorescence (XRF) technology to measure sulfur content
XRF analysis is rapid (taking seconds or minutes), non-destructive, and requires little sample preparation. The global petroleum community trusts XRF spectrometers for upstream and downstream quality control, and it is also a common technique used by on-shore test laboratories. The same testing can be performed reliably by minimally trained staff on a ship following accepted test methods such as ISO 8754, IP 336 and ASTM D4294.
Our range of XRF analysers is easy to operate, requiring minimum user training. Self-contained and requiring no gas purge, the benchtop Lab-X3500 and the handheld X-MET8000 deliver cost-effective sulfur analysis at the laboratory or on-board a ship. The X-MET is fully portable and can be taken from ship to ship, port to port, if spot-checks are required. Potentially expensive sample spills or cup leakages are prevented by the use of our simple-to-assemble safety window. The analysers are factory-calibrated using reference materials according to industry standard test method procedures. With an intuitive user interface, operators also have the ability to create their own calibrations to meet other applications requirements.
As maritime emissions regulations change, XRF can be depended upon to provide fast, reliable and easy fuels analysis.
Choosing the right XRF analyser for your needs
At Hitachi High-Tech, we are able to provide you with both benchtop analysers (Lab-X3500) which are ideal on-board a ship or in a lab, and field-portable analysers (X-MET8000).
Use the below comparison table to choose the right model for your needs:
|Conform to ASTM D4294, ISO 8754, IP 336||Yes||Yes|
|Helium purge needed||No||No|
|Automatic correction for temperature/pressure variation for maximum results stability||Yes||Yes|
|Long-term drift correction (i.e. re-standardisation; no need for full recalibration)||Yes||Yes|
|Spill and contamination protection||Yes||Yes|
|Factory calibration||Yes (standard)||Yes (on request)|
|Battery operation||No||Yes; Li-ion battery (up to 10-12 hours battery life);|
|Mains power operation||Yes||Yes|
|Data management||Results automatically printed on integrated printer after analysis||Results automatically stored on analyser; exportable to USB (PDF or CSV), PC, smartphone, and cloud service|
|Printer||Yes, integrated||Portable Bluetooth printer, optional|
|Other||—||Requires light stand or benchtop stand for the analysis of liquids|
Mikko Jarvikivi, Product Manager, shares his tips on how to get the best measurement with the Vulcan handheld laser analyser.
1) Cleaning The Vulcan
Even though the Vulcan’s measurement window is recessed and well protected, it’s essential that you clean the measurement window from dust and burn residue daily, or more if you are analysing large amounts of samples. Wipe the measurement window clean with the cotton buds that are supplied by opening the nose lid by opening the nose lid with tool provided. If the cotton bud doesn’t clean measurement window completely, dip a new one in pure ‘optical grade’ (99.5%) isopropanol and wipe again. Don’t use detergents or other alcohols to clean the window as this can leave a film on the window surface and compromise results.
Clean the camera window as well with a cotton bud at the same time.
2) Turning On Your Vulcan
Ensure the battery is fully charged. Charging the battery takes around 4-5 hours and you will get around 8-10 hours of battery life with typical usage. Measuring in cold or hot environment might slightly reduce battery life. Your Vulcan will come with two batteries to ensure no interruptions to your work routine.
It takes about 30 seconds for your Vulcan to turn on. Now is a good time to put your wrist strap on, this provides extra protection for the analyser.
You’ll need to put in your PIN code to access your Vulcan. The default PIN code is “1111”.
Remember to always wear laser safety goggles whilst operating a Class 3B laser. Pair of safety goggles is supplied with each instrument.
3) Checking The Performance With Supplied Check Sample
We always provide a certified check sample that you can use to verify performance. It’s good practice to verify performance every day. Store the check sample in a clean and dry environment and remove surface dirt before taking a measurement.
Place the analyser firmly against the sample so it’s in direct contact so there is no gap between the sample and analyser. Cover both the measurement window and proximity sensor window. The red indicator light will flash when the instrument is ready to take a measurement.
Pull the trigger and hold until you hear the ‘measurement complete’ sound. The result will show up on the screen. Check the grade ID and its chemistry, and compare them to the certificate. Typically the results should be within 5-10% of the certified values.
Make sure you move the analyser between measurements and avoid measuring exactly from the same location.
If you’ve not used a Vulcan before, find out more or contact us for a demo.