Sample Injection for Real Time Analysis (SIRTA) Using GC-MS with Cold EI

Oneg Elkabets, School of Chemistry, Tel Aviv University , Tel Aviv, Israel (Onegelkabets@mail.tau.ac.il)
Benny Neumark, School Of Chemistry, Tel Aviv University , Tel Aviv, Israel
Aviv Amirav, School Of Chemistry, Tel Aviv University , Tel Aviv, Israel

There is a continual demand for advanced methods and instruments for real-time analyses. Presently, more than 85 ambient desorption ionization techniques have been described. Most of these techniques (like DART/DESI/ASAP) are grounded in ambient desorption ionization technology, often in open environments. However, these soft ionization methods provide limited identification information since the produced mass spectra cannot be identified using mass spectral libraries like NIST. Furthermore, they resemble flow injection techniques in LC-MS systems, with the primary distinction being the necessity to dissolve samples in a solvent for flow injection analysis. Additionally, these methods require substantial hardware modifications.

We developed a new real-time analysis method named “SIRTA” (Sample Injection for Real-Time Analysis) using GC-MS with Cold EI. This newly developed method imposes no need for any supplementary or additional instrumentation thus it is characterized by zero added cost.

For SIRTA, the standard GC column is replaced with a 1 m long 0.1 mm I.D. fused silica capillary that connects the injector to the MS transfer-line of Cold EI. Similar to flow injection in MS of LC-MS systems, we touch the sample using a thin glass rod and dissolve it in a solvent within a 1 ml vial. Subsequently, the vial is placed in the GC-MS auto-sampler while using a standard syringe for injection. The analysis takes below one minute (0.2-0.7 min), ensuring rapid and consecutive analyses. SIRTA was explored with various prescription and illicit drugs, cannabis, petroleum samples and synthetic organic compounds. Cold EI uniquely enables SIRTA since it enables the use of its fly-through ion source during the elution of solvents.

SIRTA combines flow injection MS of LC-MS features in the low-cost single quadrupole MS of GC-MS, avoiding hardware modifications and enabling the installation of a parallel GC column from a second injector for GC-MS with Cold EI analysis with separation alongside SIRTA.