Abstract
Amino-terminated alkyl MWCNTs (MWCNTs-R-NH2), synthesized by chemical modification of the nanotube skeleton by nucleophilic substitution with 2,2′-(ethylenedioxy)diethylamine, were successfully used as stationary phases for gas chromatographic separation of esters and chloroaromatics. The presence of alkyl chains with polar embedded groups made the functionalized MWCNTs (f-MWCNTs) a mixed-mode GC separation material able to interact in different ways with the analytes. Compared with non-functionalized MWCNTs (nf-MWCNTs), MWCNTs-R-NH2 had higher selectivity, enhanced resolution, and optimum retention behaviour, and they were proved to perform better than the commercial stationary phase Porapak QS (PQS), claimed to be suitable for similar applications. The so-prepared stationary phase was used for analysis of a synthetic mixture containing different classes of analytes, viz. esters, ketones, alcohols, alkanes, and aromatic hydrocarbons, and finally used for investigation of similar real matrices. In particular, the constituents of a commercial paint thinner were determined by direct injection of the sample, with good reproducibility (inter-day precision RSDs from 5 to 19%). Two unknown samples of commercial white spirit were also analysed for determination of the aromatic hydrocarbon content, and their composition was profiled on the basis of the different compounds identified.
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Abbreviations
- CNTs:
-
Carbon nanotubes
- GC:
-
Gas chromatography
- HPLC:
-
High-performance liquid chromatography
- MWCNTs:
-
Multi-walled carbon nanotubes
- f-MWCNTs:
-
Functionalized multi-walled carbon nanotubes
- nf-MWCNTs:
-
Non-functionalized multi-walled carbon nanotubes
- MWCNTs-R-NH2 :
-
Amino-terminated alkyl-functionalized multi-walled carbon nanotubes
- OLLSR:
-
Ordinary linear lower-squares regression
- PQS:
-
Porapak QS
- RSD:
-
Relative standard deviation
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Acknowledgments
This work was principally supported by FAR (Fondo Ateneo per la Ricerca) of the University of Pavia (Italy). The authors want to thank Mr Silvano Lunati (Department of Chemistry, University of Pavia) for his technical support, and the Euroanalysis Commission for the best-work prize which was awarded to this work.
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Published in the special issue Euroanalysis XVI (The European Conference on Analytical Chemistry) with guest editor Slavica Ražić
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Speltini, A., Merli, D., Dondi, D. et al. Improving selectivity in gas chromatography by using chemically modified multi-walled carbon nanotubes as stationary phase. Anal Bioanal Chem 403, 1157–1165 (2012). https://doi.org/10.1007/s00216-011-5606-y
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DOI: https://doi.org/10.1007/s00216-011-5606-y