SRNU MEPhI scientists have found an approach for finer control of fragmentation of fragile molecules during electron impact ionization, which will improve the sensitivity and accuracy of mixture composition determination in petrochemical, pharmaceutical and forensics-related tasks. The study was published in the highly ranked scientific journal Talanta.

Gas chromatography with mass spectrometry (GC-MS) is the most widely used analytical method today for determining the molecular composition of mixtures. It is a highly accurate and sensitive method widely used in petrochemical, pharmaceutical, forensic and other industries. An integral step in the analysis for GC-MS is ionisation, usually by electron impact.

"Despite the well-known advantages of electron ionisation, its disadvantage is the uncontrolled fragmentation of molecular ions of some classes of compounds with fragile molecules. For example, compounds such as alkanes fragment too much and there is little or no peak from a whole molecule in the spectrum.

 Researchers  from SRNU MEPhI proposed a fairly easy to implement method of electron ionization in a molecular jet, formed by a capillary assembly. With the capillaries can be simply and efficiently form a region of high local pressure in the region of ionization, which allows to reduce the internal energy of the molecules and eventually reduces the probability of fragmentation.

As a result of experiments the authors found a relative increase in the molecular peak for different compounds by a factor of 5-20 compared to the use of electron impact ionization in the conventional mode.

It is anticipated that the modified ion source can be optionally retrofitted to GC-MS instruments to enhance their capabilities.

Scientists plan to continue their research, as they found a number of interesting effects during the first experiments. A better understanding of what is going on will allow the researchers to improve the effectiveness of the proposed approach.