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Highly sensitive determination of 2,4,6-trinitrotoluene and related byproducts using a diol functionalized column for high performance liquid chromatography.

Gumuscu B, Erdogan Z, Guler MO, Tekinay T - PLoS ONE (2014)

Bottom Line: The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts.When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold.The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions.

View Article: PubMed Central - PubMed

Affiliation: UNAM, Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey; MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands.

ABSTRACT
In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95-98%. The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation.

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Molecular structures of TNT and its byproducts.
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pone-0099230-g001: Molecular structures of TNT and its byproducts.

Mentions: The hydroxyl groups in diol column are electron donors. Aromatic amines are electron acceptors, having the ability to undergo charge-transfer complexation with dative and no bond resonance hybrid structures. The nitro group of aromatic amines consists of highly electronegative N and O atoms, which cause the polarization of N−O bond [27]. The nitro group polarization leads the formation of charge-transfer complexes between nitro group of analyte and the column material [28]. Accordingly, the donor-acceptor interactions between the acceptor nitro group and the donor hydroxyl group become the driving force for separation [29], [30]. For TNT, the strong electron affinity of −NO2 groups draw the 2, 4, and 6 positions to be electron deficient; therefore, the nitrogen atoms with a lone pair of electrons in amines donate electrons to form n→π charge-transfer complexes [14], [31]. TNT and its byproducts have high charge-transfer capabilities [29]. The order of the relative charge transfer capability for TATD is thought to be TNT; 2,4-DNT; 2-6-DNT; 2-ADNT; and 4-ADNT; as TNT is the highest [32]. Therefore, TNT retarded before than 2,4-DNT. The hydrogen bonds of 2,6-DNT are in ortho position and have effect on the retention of this molecule later than 2,4-DNT. Next, hydrogen bonds in amino groups might have a negative effect in charge transfer capability of ADNT molecules. The amino groups in 4-ADNT are in free position and the molecule is relatively a weaker acceptor, consequently 4-ADNT was observed after 2-ADNT (Fig. 1 and 2).


Highly sensitive determination of 2,4,6-trinitrotoluene and related byproducts using a diol functionalized column for high performance liquid chromatography.

Gumuscu B, Erdogan Z, Guler MO, Tekinay T - PLoS ONE (2014)

Molecular structures of TNT and its byproducts.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4048276&req=5

pone-0099230-g001: Molecular structures of TNT and its byproducts.
Mentions: The hydroxyl groups in diol column are electron donors. Aromatic amines are electron acceptors, having the ability to undergo charge-transfer complexation with dative and no bond resonance hybrid structures. The nitro group of aromatic amines consists of highly electronegative N and O atoms, which cause the polarization of N−O bond [27]. The nitro group polarization leads the formation of charge-transfer complexes between nitro group of analyte and the column material [28]. Accordingly, the donor-acceptor interactions between the acceptor nitro group and the donor hydroxyl group become the driving force for separation [29], [30]. For TNT, the strong electron affinity of −NO2 groups draw the 2, 4, and 6 positions to be electron deficient; therefore, the nitrogen atoms with a lone pair of electrons in amines donate electrons to form n→π charge-transfer complexes [14], [31]. TNT and its byproducts have high charge-transfer capabilities [29]. The order of the relative charge transfer capability for TATD is thought to be TNT; 2,4-DNT; 2-6-DNT; 2-ADNT; and 4-ADNT; as TNT is the highest [32]. Therefore, TNT retarded before than 2,4-DNT. The hydrogen bonds of 2,6-DNT are in ortho position and have effect on the retention of this molecule later than 2,4-DNT. Next, hydrogen bonds in amino groups might have a negative effect in charge transfer capability of ADNT molecules. The amino groups in 4-ADNT are in free position and the molecule is relatively a weaker acceptor, consequently 4-ADNT was observed after 2-ADNT (Fig. 1 and 2).

Bottom Line: The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts.When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold.The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions.

View Article: PubMed Central - PubMed

Affiliation: UNAM, Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey; MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands.

ABSTRACT
In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95-98%. The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation.

Show MeSH
Related in: MedlinePlus