Silica-based 2-(N,N-dimethylamino)-1,3-propanediol hydrophilic interaction liquid chromatography stationary phase for separating cephalosporins and carbapenems.

A silica-based stationary phase bearing both hydrophilic hydroxyl and amino groups was developed by covalently bonding a small molecular N,N-dimethylamino 1,3-propanediol moiety onto silica beads via copper(I)-catalyzed Huisgen azide-alkyne 1,3-dipolar cycloaddition (CuAAC). This new stationary phase showed good HILIC characteristics and high column efficiency (the theoretical plate number is up to 37000 plates m(-1) in the case of inosine) in the separation of polar compounds, such as nucleosides and bases, organic acids, cephalosporins, and carbapenems.

Click N-benzyl iminodiacetic acid: novel silica-based tridentate zwitterionic stationary phase for hydrophilic interaction liquid chromatography.

Iminodiacetic acid (IDA) is dicarboxylic acid amine, which may produce stronger interaction with polar or charged compounds than bidentate α,ß-amino acid. In this article, a novel type of tridentate zwitterionic HILIC stationary phase was prepared by covalently bonding N-benzyl IDA on silica gel via copper(I) catalyzed Huisgen azide-alkyne 1,3-dipolar cycloaddition (CuAAC). The structure of this stationary phase and all related intermediates was confirmed by NMR, FT-IR, MS spectrum and elemental analysis. The new stationary phase showed good HILIC characteristics and high column efficiency (the theoretical plate number is up to 44000 plates m(-1) in the case of guanosine) in the application of separation of polar compounds, including organic acids, organic bases, as well as highly polar and hydrophilic compounds, such as cephalosporins and carbapenems. Most of them displayed good peak shape and selectivity.

Coupling of comprehensive two-dimensional gas chromatography with quadrupole mass spectrometry: application to the identification of atmospheric volatile organic compounds.

Observation data of atmospheric volatile organic compounds (VOCs) are highly needed in air quality assessment, photochemical mechanism study, and emission control policy-making, while it has been a challenge to accurately and comprehensively measure them. Comprehensive two-dimensional gas chromatography (GC×GC) is one of the advanced techniques in analysis of complex mixtures, providing a good choice for measurement of VOCs. However, the requirement for a fast detector limits the application of quadrupole mass spectrometry (qMS) in GC×GC analysis. This paper presents a method of a common qMS detector coupled with GC×GC to the identification of atmospheric VOCs. About 125 VOCs including alkanes, alkenes, aromatics, oxygenated hydrocarbons, and halocarbons were identified in the measurement of standard gas mixtures and/or urban air samples from Beijing. The results were applied to the analysis of GC×GC-FID by one to one correspondence of peaks of the equivalent compounds between the GC×GC-FID and GC×GC-qMS chromatograms, and the retention times of the identified components in GC×GC-FID in turn undertake the qualitative analysis without the further help of MS. The wrap-around phenomenon which may confuse the match of peaks was discussed in detail. The cooperation of GC×GC-FID and GC×GC-qMS which assists the identification makes the GC×GC exploration more affordable and yet practical on both qualitative and quantitative analysis. The method and the identified results can be expanded to analyze other volatiles.