New ion trap to create the most accurate mass spectrometer
Jan Pavelka / Wikimedia Commons
Scientists from the Skolkovo Institute of Science and Technology have modified the mass spectrometer to improve the efficiency of molecular mass measurements. To this end, they have developed an electromagnetic measuring “ion trap” that allows, by maintaining a vacuum, to achieve maximum accuracy in the case of ultra-high magnetic fields. The results of the work were published in the journal Analytical Chemistry.
The “ion trap” is a cylinder of electrodes, inside it electric and magnetic fields are created, in which the ions of the test substance rotate. From the frequencies of rotation of the ions, you can determine their exact mass. In this case, it is important that the ions rotate predictably, for this the electric field must have a special shape, be harmonized, and the traps must be dynamically harmonized.
The first dynamically harmonized trap (DHC) was invented in 2011. The name is due to the fact that the real field is not harmonious, but is perceived by the ions in this way due to their rapid rotation. DHC is actively used in mass spectrometers. The accuracy of mass measurements should increase linearly with increasing magnetic field, but in fact it increases much more slowly than expected.
Skoltech scientists suggested that this is due to the lack of vacuum in the trap, even when using the most advanced pumps. To solve this problem, they developed a Zig-Zag Cell that is open at both ends, allowing residual gases to be pumped out of the trap without obstruction to maintain the required vacuum.
“Now this device is being created in our laboratory. On it we will conduct experiments and check if our assumptions were correct. But if they are correct, then the created trap will again return the linear dependence of the accuracy of measuring the mass spectrum on the magnetic field, which will give better accuracy at very high magnetic fields. And since the accuracy already grows with increasing field, this means that the trap will potentially create the most accurate mass spectrometer of all existing mass spectrometers, ”says co-author of the study Anton Lioznov.
Mass spectrometers with a new type of trap will improve the accuracy of the analysis of biological samples and such complex mixtures as oil, where up to 400 thousand different compounds have already been detected.