WHAT’S HOT IN METAL
Spectrometer wars: It’s ICP-MS over ICP-OES
When comparing ICP Mass Spectrometry (Inductively Coupled Plasma Mass Spectrometry) and ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry), the sample introduction and plasma formation are the same, but the similarity ends there. ICP-MS instruments exhibit superior overall performance, providing lower detection levels, greater sensitivity, and better elemental coverage—which is good news for our clients. More on that later.
Let’s start with detection: ICP-OES detects photons of light emitted from the plasma, while ICP Mass Spectrometry detects ions at a specific mass using a quadrapole-based analyzer. The quadrapole filters the ion stream, allowing only one element at a time to reach the detector. This increases sensitivity and greatly reduces spectral interference, which is a limitation in ICP-OES. Although the actual run time per sample is the same between the two techniques, the ICP Mass Spectrometry gains the advantage with Limits of Quantitation (LOQs), typically 10 times lower than ICP-OES. Beryllium is especially sensitive by ICP Mass Spectrometry with an LOQ of 0.0075 ug per filter, 20 times lower than the ICP-OES LOQ.
The final advantage is flexibility for our clients. ICP Mass Spectrometry has the ability to run nearly any element across the mass range compared to the pre-selected lines on the ICP-OES. This means that if you, as an SGS Galson client, request it, we can method-develop elements not currently found in our fee schedule. All of the advantages of ICP Mass Spectrometry are available to our clients for a small increase per sample, due to the higher operating costs associated with the ICP Mass Spectrometry technology.
Choosing the best wipe media: the Right Tool for Plasma Spectrometry
Although SGS Galson currently supports the use of Ghost Wipes, Lead Wipes, and 2×2 gauze wipes, we have discontinued supplying the Ghost Wipes because we have found a superior alternative: the Lead Wipe.
The Lead Wipe, so named by the manufacturer, offers a host of advantages. First, it can be used for nearly any metal. It’s convenient: the Lead Wipe is individually packaged and pre-moistened. Additionally, it digests very well and does not require filtering, eliminating a potential source of error. And the final extract is not viscous, which improves the analytical data and reduces wear and tear on the instruments, improving turnaround time for results. Finally, the Lead Wipe provides better detection limits. Our current LOQ on Ghost Wipes for lead is 3.0 ug compared to 1.2 ug on the Lead Wipe.
Check our Sampling and Analysis Guide, available at sgsgalson.com or in hard copy on request. You’ll be able to compare the LOQs for the different types of wipe media on a per-element basis, and find out which elements are not recommended at all on a specific type of wipe due to background interference.
Developing a finer filter for welder well-being
Welding can be an extreme health hazard. Breathing welding fumes can cause symptoms ranging from mild irritation of the respiratory tract to chronic systematic metal poisoning, even death, depending on the metal being welded and which protective equipment is being used.
The welding industry has become increasingly aware of these dangers, and has been proactive in working to reduce or eliminate them. The effectiveness of the safety measures used must be tested, however, to evaluate existing guidelines and further improve working conditions.
Recently, OSHA implemented a change to one of the monitoring procedures. A welder’s breathing zone was formerly analyzed by collecting a specified amount of air on a 37 mm filter, outside the welder’s helmet. Studies performed by a wide range of professionals, however, have shown that the metal fume concentrations can vary widely just by moving the filter location from outside the helmet to inside. Since the air entering the worker’s body is directly inside the helmet, this sampling change makes sense.
Some helmets, though, cannot easily and comfortably accommodate the traditional 37 mm filter. In these cases, a 25 mm filter and cassette may be used, but care must be taken not to overload the filter. Due to the decreased surface area of a 25 mm filter, collecting a smaller volume of air may be necessary. As part of our ongoing drive to meet our clients’ needs, SGS Galson has already developed a method for the use of a 25 mm PVC
filter that can be used for this sampling modification.
If you have questions about any existing or new analytical services or methodologies in plasma spectrometry (ICP Plasma Spectrometry or ICP-OES), please call us today at 888-432-LABS or use our IHLive online chat at sgsgalson.com. We’re here to help you.