Separation strategies for the determination of residues of explosives in soils using micellar electrokinetic capillary chromatography

Abstract

Abstract. Micellar electrokinetic capillary chromatography (MEKC) separation strategies for the determination of residues of explosives in soils are presented. Compared to former publications, the number of explosives determined was increased up to 24 compounds in which all EPA priority substances are included. Separation characteristics were investigated as a function of different organic modifiers. Using 1 vol% of methanol, separation was realized for all 24 compounds, including all of the isomers of the monoand dinitrotoluenes. Furthermore, the lipophilic and hydrophilic parts of the surfactant were varied, and the best separation characteristics were obtained with sodium dodecyl sulphate (SDS). Even the suitability of mixed micelles for the analysis of nitroaromatics was tested. With the help of mixed micelles consisting of SDS and the amphoteric surfactant SB-12, separation of 22 out of 24 explosives was realized. With significantly changed selectivities, complete separation required less than 12 minutes.

The effect of operating variables in microemulsion electrokinetic capillary chromatography

“…Methanol also effected the migration time of all components in the test-mixture and it had very similar affects as in MEKC [24]. By changing the viscosity and the permitivity of the buffer, methanol slows down the EOF.…”

Application of Sodium Dodecyl Sulfate Micellar Electrokinetic Chromatography (SDS MEKC) for the Rapid Measurement of Aqueous Phase 2,4,6-Trinitrotoluene Metabolites in Anaerobic Sludge: A Comparison with LC/MS

“…In viewing Table 3 one can assume that a better resolution for TAT is possible through the addition of SDS, as it would increase the partial volume of the micelles and the total amount of TAT residing in the pseudostationary phase. Mussenbrock and Kleibohhmer (17) reported the use of sodium laureth sulfate, a surfactant with greater lipophilicity than SDS due to the placement of ethoxy groups in its aliphatic chain, to be advantageous for the separation of polar compounds such as TAT. However, in view of the excellent selectivity and short run times obtained, no optimization of the buffer composition was attempted.…”

“…SDS MEKC appeared to be capable of resolving both polar and nonpolar analytes with little pretreatment, and this made the method attractive for the analysis of unstable intermediates. The majority of SDS MEKC applications have admittedly been focused on biochemical and pharmaceutical analyses (16), but the technique was demonstrated to resolve explosive mixtures (17) and some explosive detonation products (18). The method was also applied to the monitoring of various energetic contaminants and their corresponding metabolites in degradative bioprocesses (19) (20).…”

Micellar electrokinetic chromatography: Current developments and future

“…The application of mixed micellar systems (MMS) for MEKC has been the focus of a considerable interest during the last decade because of their demonstrated utility for the analysis of highly related compounds. MMS have been used to solve selectivity problems arising in complex mixtures submitted to MEKC in one surfactantbased solutions [77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93]. All the possible combinations of different types of surfactants have been almost applied, but the most popular mixed aggregates are constituted by one neutral (nonionic, very often Brij-35 or Tween 20) and one anionic surfactant (SDS in most cases) [77][78][79][80][81][82][83][84][85].…”