A fast and cheap method for separating isotopes

Everything that surrounds us in the world contains unique chemical markers. These markers, called isotopes, can reveal to scientists the origins of the particles that make up the materials, where they went and what happened to them during this period and through this

Everything that surrounds us in the world contains unique chemical markers. These markers, called isotopes, can reveal to scientists the origins of the particles that make up the materials, where they went and what happened to them during this time and way. However, performing such an analysis has so far been complex and expensive. Now, chemists from Stanford University (Stanford) in the USA have developed a new, simpler and cheaper method for analyzing isotopes.

"Everything is done through smoke and mirrors," said chemist Richard Zare, in his most literal description of the cutting-edge method. The device he and his colleagues developed burns chemical samples to obtain a gas, which then flows through a laser beam that splits back and forth through a set of mirrors fixed in a special container.

All atoms of a certain element have the same number of protons in their nucleus, but they can contain a variable number of neutrons. Carbon, for example, always contains six protons, but the number of neutrons in its nucleus can vary from six to seven and eight. Each such different element is an isotope of carbon.

The researcher had an idea in which the different isotopes can be distinguished by the color, or the wavelength, that is returned from the laser beam following its encounter with smaller fragments obtained by the decomposition of the original materials.

"Think of them as identical balls with different colors," explains the researcher. Our new tool is able to calculate the composition of isotopes in a sample simply by "counting the colors and comparing them." This principle also makes the device more versatile than mass spectrometers available today because the new device is able to analyze the isotope composition of different elements at the same time without the need for re-calibration for each element separately.

The equipment required for the modern method is smaller, cheaper, lighter and more portable than previous methods, and simple to use. It has the ability to demonstrate the many advantages of isotope analysis and bring it easily within the reach of a variety of researchers, who until now have been reluctant to use the expensive equipment due to its high cost, when they needed it, the researcher explains. He and his colleagues report their method in the online version of the scientific journal Proceedings of the National Academy of Sciences.

Isotope analysis is used in a variety of research fields, including: geochemistry, medicine and climate science. To this day, the analysis is done using an isotope ratio obtained by a mass spectrometer device, which works by breaking apart the isotopes with an electric current and using a magnet to separate the isotopes according to their mass - the more neutrons there are, the greater the mass. One such device can cost about a million dollars. In addition to being expensive and heavy, the use of mass spectrometers available today requires experienced technicians to operate them correctly.

The new device, which uses a spectroscopic method of "cavity ring-down spectroscopy" has possible applications in diverse fields such as medicine, geology and oenology (making wine), the researcher notes. "There are people who are willing to pay a lot of money for good wine," explains the researcher. "If I can measure the isotopic composition, I can tell you with confidence whether you're paying big money for the real thing or not."

Since the distribution of unique isotopes of the elements is greater than others in certain sites, the ratio of the different isotopes in a complex mixture can be used as a sort of travel diary - it can reveal to you the history of the mixture, whether it originated in different countries or not, whether it originated in a particular tissue in the human body or from a period of time more ancient Determining the history of a mixture of substances by measuring the ratio of isotopes in them is known as isotopic analysis.

As an example, the researcher explains that certain plants, such as corn, contain a greater amount of carbon-13 than other plants. Since Americans tend to eat more corn and corn products than Europeans, isotopic analysis of their breath will show a greater amount of carbon-13.

Doctors and pharmacists can use isotopic analysis to measure the targeting accuracy of selective drugs by testing urine and breath samples to see if the appropriate organs have broken it down as intended. In addition, climate scientists can learn a lot about the conditions that prevailed on Earth in earlier times by examining the substance carbon dioxide trapped in the core of glaciers, explains the researcher.

The researchers, in collaboration with the start-up company Picarro Inc, created a prototype of the device and successfully tested its performance by measuring the isotopes of carbon in various organic compounds such as methane, ethane and propane. The cumbersome magnets, which are the most expensive components in mass spectrometers, are not required at all in the new device, so the costs are much lower while obtaining a sufficient level of performance, according to the researcher. Another advantage: the device can be used without special and long training.

Existing devices for isotopic analysis, based on mass spectroscopy, can reach a weight of about seven hundred kilograms and occupy a space similar to a large freezer, such as exists in ice cream shops. Once the prototype is fully developed and commercialized, "it will fit the size of a car seat," notes the researcher. This mobility will be able to advance the isotopic analysis directly to the field, whether it is the doctor's office or whether it is the winemaker's vineyard. At the same time, the team sees room for further improvements.

The isotope ratio measurements of the new device are accurate to within one to three units per thousand units, which is enough accuracy to be competitive with the spectroscopy devices available today. "Our goal is to be better and actually replace the isotopic analysis done through mass spectroscopy," explains the researcher. He sees this goal being achieved within five to ten years.

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