Dielectric Barrier Discharge Ionization in Characterization of Organic Compounds Separated on Thin-Layer Chromatography Plates

Abstract

A new method for on-spot detection and characterization of organic compounds resolved on thin layer chromatography (TLC) plates has been proposed. This method combines TLC with dielectric barrier discharge ionization (DBDI), which produces stable low-temperature plasma. At first, the compounds were separated on TLC plates and then their mass spectra were directly obtained with no additional sample preparation. To obtain good quality spectra the center of a particular TLC spot was heated from the bottom to increase volatility of the compound. MS/MS analyses were also performed to additionally characterize all analytes. The detection limit of proposed method was estimated to be 100 ng/spot of compound.

Flowing atmospheric pressure afterglow combined with laser ablation for direct analysis of compounds separated by thin-layer chromatography

“…The most intense background ion is visible at m / z 279, corresponding to di- n -butyl phthalate (DBP), a plasticizer leaking from the tubing used in our setup. The mixture of five pyrazole derivatives has been used as an example to show proof of concept, because these compounds are well resolved on the TLC plate and, in our previous experiments [ 25 ], all these compounds were observed as protonated molecules on the mass spectra. The smallest difference in R f factor equal to 0.09 is between compounds 3 and 1, which can be clearly seen in the BPC.…”

“…Synthesis of pyrazole derivatives used in this work as analytes for the TLC-FAPA technique has been described in detail in our previous publication [ 25 ]. For all TLC-FAPA experiments, the Merck Millipore TLC silica gel 60 F 254 aluminum sheets was applied.…”

“…Recently, many direct-sampling TLC-MS techniques, which allow obtaining mass spectra of the analytes by desorption and subsequent ionization directly from the TLC plate, such as TLC-matrix-assisted laser desorption/ionization (TLC-MALDI) [ 19 ], TLC-desorption electrospray ionization (TLC-DESI) [ 20 ], TLC-electrospray-assisted laser desorption/ionization (TLC-ELDI) [ 21 ], TLC-easy ambient sonic spray ionization (TLC-EASI) [ 22 ], TLC-direct analysis in real time (TLC-DART) [ 23 ], and TLC-atmospheric-pressure chemical ionization (TLC-APCI) [ 24 ] have been developed. Our group has recently presented the TLC-dielectric barrier discharge ionization (TLC-DBDI) setup and successively used it for characterization of small organic compounds separated on TLC plates with thermal desorption [ 25 ]. TLC-MS setups have been applied for identification of fatty acids [ 26 , 27 ], synthesis products [ 28 ], alkaloids [ 29 ], and drugs [ 30 ].…”

Electrochemical generation of selegiline metabolites coupled to mass spectrometry

“…Helium (purity 99.996%) at the flow rate 1 L/min was used to create plasma by applying potential of 8 kV to copper electrodes. The more detailed description of all DBD source parameters was published earlier [22].…”

“…The ionization of all compounds was achieved with the helium-based dielectric barrier discharge ionization (DBDI) source [21,22]. Helium was used as a discharge gas at a flow rate of 1 L/min.…”