Isomeric differentiation of chloroanilines by gas chromatography-mass spectrometry in combination with tosylation

Star-poly(ε-caprolactone) as the stationary phase for capillary gas chromatographic separation

This work presents the separation performance of star-poly(ε-caprolactone) (star-PCL) as the stationary phase for capillary gas chromatography (GC). The statically coated star-PCL column showed a column efficiency of 3345 plates per m and moderate polarity. Importantly, the star-PCL column exhibited high selectivity and resolving capability for more than a dozen mixtures covering a wide-ranging variety of analytes and isomers. Among them, the star-PCL column displayed advantageous resolving capability over the commercial DB-1701 column for aromatic amine isomers such as toluidine, chloroaniline and bromoaniline. Moreover, it was applied for the determination of isomer impurities in real samples, showing good potential in GC applications.

This work presents the separation performance of star-poly(ε-caprolactone) (star-PCL) as the stationary phase for capillary gas chromatography (GC).

Differentiation of isomeric methylanilines by imidization and gas chromatography/mass spectrometry analysis

RATIONALE

Carcinogenic o-methylaniline is one of the banned aromatic amines in azo dyes, but it is very difficult to distinguish it from its noncarcinogenic isomers due to their identical retention time on chromatography and similar mass spectra.

METHODS

Imidization of the isomeric methylanilines was carried out by treatment with benzaldehyde under mild conditions. The formed derivatives were analyzed by gas chromatography/mass spectrometry (GC/MS). Theoretical calculations were carried out on the Gaussian 03 program by using the density functional theory method at the B3LYP/6-311+G(d,p) level.

RESULTS

Imidization of methylanilines occurred easily and gave rise to the corresponding N-methylbenzylidene benzenamines. The isomeric derivatives were completely separated by GC, and thus the three isomeric methylanilines could be determined simultaneously. Due to the ortho effect, the derivative from o-methylaniline has a characteristic fragment ion at m/z 118 with a stable bicyclic structure, and it could be easily differentiated from the meta- and para-isomers in electron ionization mass spectrometry.

CONCLUSIONS

These results provided a promising solution for simultaneous determination of isomeric methylanilines.

Simultaneous determination of isomeric substituted anilines by imidization with benzaldehyde and gas chromatography-mass spectrometry

The chromatographic separation of several isomeric anilines is a challenging issue. Herein, a simple method for the simultaneous determination of four groups of isomeric primary aromatic amines, including chloroanilines, methylanilines, methoxylanilines, and dimethylanilines, was presented. In this method, all of the 15 primary aromatic amines were easily transformed into the corresponding imine derivative by treatment with benzaldehyde under mild conditions. The formed isomeric imine derivatives were completely separated on a commercial capillary gas chromatography column. The effects of several derivatization parameters were investigated and optimized. Linearity in the optimized method ranged from 0.050 to 50 μg/mL with the squared correlation coefficients (R² ) between 0.9981 and 0.9999. Reasonable reproducibility was obtained, with the intraday relative standard deviation (N = 5) ranging from 0.89 to 4.57% and interday relative standard deviation ranging from 2.26 to 7.69% at the concentration of 5.0 μg/mL. The developed method has been successfully applied to determine these isomeric aromatic amines in real samples.