Where Is ICP-MS Making a Difference?
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Inductively coupled plasma-mass spectrometry (ICP-MS) is an analytical technique that allows sample identification by ionizing, separating and detecting analyte components. ICP-MS can analyze almost all elements of the periodic table, is very sensitive, can be used on small sample volumes and is suitable for high sample throughput. The technique can be used across a broad range of applications, a few of which we will explore here.
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Short-Lived Volcanic Landmass Offers Some Microbial Surprises
In a study published in mBio, researchers discovered a unique microbial community that metabolizes sulfur and atmospheric gases on Hunga Tonga Hunga Ha'apai (HTHH), an island created by a submarine volcano eruption in 2015.
The island’s emergence allowed the first-ever comprehensive study of microorganisms on this type of island system at such an early stage of ecosystem development. Soil samples were collected from HTHH and returned to the lab for DNA extraction and sequencing. The researchers used lithium borate fusion ICP-MS to measure the composition of trace elements in the sediment. The study authors believed they would find organisms observed when a glacier retreats or other typical early colonizer species – but instead, they discovered a unique group of bacteria that metabolize sulfur and atmospheric gases.
“One of the reasons why we think we see these unique microbes is because of the properties associated with volcanic eruptions: lots of sulfur and hydrogen sulfide gas, which are likely fueling the unique taxa we found,” said Nick Dragone, Cooperative Institute for Research in Environmental Sciences (CIRES) PhD student and lead author of the study. “The microbes were most similar to those found in hydrothermal vents, hot springs like Yellowstone and other volcanic systems. Our best guess is the microbes came from those types of sources.”
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Could Egg Powder Help To Combat Malnutrition?
Results of a study published in Frontiers in Nutrition show that egg powder could have the potential to improve the nutritional situation of children in deprived areas.
"Studies show that adding one egg a day to complementary food can help reduce the incidence of underweight in older infants by 74%, as well as counteract the so-called ”stunting” effect," says Veronika Somoza, director of the Leibniz Institute for Food Systems Biology at the Technical University of Munich (LSB).
However, eggs aren't usually readily available in areas where malnutrition is part of everyday life. Compared to pasteurized whole egg, the powder form is easier to store and transport, and can be easily added to food. Despite the widespread use of the powder, little was known of its nutritional quality. Researchers from LSB set out to determine the nutrient profiles of industrially produced, pasteurized whole egg and the egg powder processed from it. The analyses show that the powder contains lower amounts of essential fatty acids, but still provides many vitamins, essential amino acids and important trace elements.
“ICP-MS measurements were carried out to examine the overall mineral composition of both products concerning nutritional quality and safety, as well as to compare possible losses of nutritive elements or concentration of potentially toxic non-essential trace elements during spray-drying” the authors write.
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Microplastics May Boost the Toxicity of Other Pollutants
A study published in Environmental Science & Technology Letters suggests that microplastics can aid in transforming pollutants into a more harmful form.
Heavy metals such as chromium (Cr) can easily attach to microplastics. When on the surface of microplastics, Cr can take on different oxidation states, and while Cr(III) is relatively safe, Cr(VI) is toxic and could harm aquatic life. To investigate how the oxidation state of Cr bound to microplastics may change when affected by UV filter molecules (a common organic contaminant found in products like sunscreen), a research team from Hong Kong Baptist University and Hong Kong Polytechnic University created mixtures of Cr and polystyrene microplastic (PSMP) particles both with and without benzophenone-type UV filters. The team used liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS) to determine the abundance of Cr(VI). The research found that microplastics could aggregate even more Cr in the presence of a UV filter, and the oxidation state of Cr was higher in the mixtures containing the filters. When exposed to mixtures containing the filters, microalgal growth was inhibited.
“Results showed that Cr uptake by PSMPs was remarkably higher when UV filters were present. This enhanced affinity was attributed to the formation of Cr–UV filter complexes together with multilayer sorption on PSMPs’ surfaces” the authors write.
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Origin of Earth’s Volatile Chemicals Revealed by Meteorites
Research from Imperial College London (ICL) has uncovered the origin of Earth’s volatile chemicals.
Volatiles, such as zinc (Zn), are elements or compounds that change into vapor from solid or liquid states at relatively low temperatures. They include the six most common elements found in living organisms, and water. Nucleosynthetic anomalies are variations in the abundance of isotopes in Solar System material. By measuring these anomalies, it is possible to constrain the origins of material that formed Earth.
In the study, published in Science, the team measured the relative abundances of the 5 different isotopes of zinc (Zn) in 18 meteorites of varying origins. Zn isotope measurements were conducted on a multiple collector-inductively coupled plasma-mass spectrometer (MC-ICP-MS). The researchers found that around half of the zinc on Earth came from asteroids originating beyond the asteroid belt that includes the planets Jupiter, Saturn and Uranus.
“This contribution of outer Solar System material played a vital role in establishing the Earth’s inventory of volatile chemicals. It looks as though without the contribution of outer Solar System material, the Earth would have a much lower amount of volatiles than we know it today – making it drier and potentially unable to nourish and sustain life” said Mark Rehkämper, professor of isotope geochemistry, ICL.
Final thoughts
While there are some challenges associated with ICP-MS, including undesired interference, expensive instrumentation and user training requirements, it is an effective technique for the detection of a wide variety of analytes and can be applied to many different areas of study. For more educational resources, events, news and products related to ICP-MS techniques and applications, explore our ICP-MS topic page here.
