Capillary electrophoretic separation of polynuclear aromatic hydrocarbons using sodium cholate in mixed aqueous–organic buffers

Capillary and microchip electrophoretic analysis of polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants which can reach the environment and food in different ways. Because of their high toxicity, two international regulatory institutions, the US Environmental Protection Agency and the European Food Safety Authority, have classified PAHs as priority pollutants, generating an important demand for the detection and identification of PAHs. Thus, sensitive, fast, and cheap methods for the analysis of PAHs in environmental and food samples are urgently needed. Within this context, electrophoresis, in capillary or microchip format, displays attractive features. This review presents and critically discusses the published literature on the different approaches to capillary and microchip electrophoresis analysis of PAHs.

Separation of hydrophobic solutes by organic-solvent-based micellar electrokinetic chromatography using cation surfactants

In this study, the separation of 13 homologous stick-like hydrophobic solutes, i.e., biphenyl nitrile derivatives, by organic-solvent-based micellar electrokinetic chromatography (MEKC) was investigated in terms of separation medium composition, species and concentration of surfactant, other additives, separation voltage and temperature. The results showed that the 13 strong hydrophobic compounds were baseline separated in 25 min with a repeatability of less than 1.3% (RSD) for migration time. The separation medium was a mixture of methanol, 2-propanol and water (58.5:10:31.5), containing 150 mM cetyltrimethylammonium bromide (CTAB) and 20 mM sodium borate. Variety of solvent composition, temperature and applied voltage all showed remarkable effect on the separation. The organic-solvent-based MEKC method proved to be superior to the aqueous MEKC and microemulsion electrokinetic chromatography (MEEKC) methods for the separation of strongly hydrophobic compounds.

Environmental analysis based on luminescence in organized supramolecular systems

The use of organized supramolecular systems-including micellar media and cyclodextrin inclusion complexes-combined with luminescence techniques in the study and determination of compounds and elements of environmental interest from 1990 to 2005 is reviewed. Analyses of environmental samples performed using fluorescence, photochemically induced fluorescence and phosphorescence spectroscopy as well as liquid chromatography, capillary electrophoresis and flow injection with luminescence detection in the presence of these organized media are described in detail.

Micellar electrokinetic chromatography of tri aza aromatic ligand compounds of iron (II): influence of bile salt type on enantiomeric separation

Micellar electrokinetic chromatography is used with a variety of bile salt micelles to separate the enantiomers of bis(8-((pyridine-2-methylene)amino)quinoline)iron(II) hexafluorophosphate, Fe(PMAQ)2(PF6)2; bis(8-((pyridine-2-methylene)amino)lepidine iron(II) hexafluorophosphate, Fe(PMAL)2(PF6)2; and bis(1-(2-pyridinyl)ethylidine)-8-aminoquinoline iron(II) hexafluorophosphate, Fe(PEAQ)2(PF6)2. The influence of ten different bile salts on the resolution of each pair of enantiomers is investigated. Significant changes in resolution are seen depending upon the bile salt used. The dihydroxy bile salts are superior to the trihydroxy bile salts in terms of resolution, and the taurine or glycine conjugated bile salts yield better results than the unconjugated bile salts. Resolution for most enantiomers is maximized in a buffer solution containing 10-15% acetone and employing either taurochenodeoxycholic or glycochenodeoxycholic acid as the bile salt. Evidence for the separation of the corresponding Fe(III) complexes is presented.

Hydrophobic interaction electrokinetic chromatography for the separation of polycyclic aromatic hydrocarbons using non-aqueous matrices

Capillary electrophoresis methodology is developed to provide a rapid, inexpensive and robust technique for screening polycyclic aromatic hydrocarbons (PAHs) in water using additive complexation. A series of conventional RPLC ion-pairing agents are investigated in three different totally non-aqueous separation solvents, and the relative role of hydrophobic interaction versus electrostatic association is evaluated. Methanol is found to provide optimal selectivity when coupled with the tetrahexylammonium cation providing total analysis times of approximately 15 min for the analysis of thirteen 2-7-ring PAH pollutants. Solid-phase microextraction is demonstrated to be an effective sample preparation technique for extraction/preconcentration of PAHs from water into methanol run buffer prior to injection.

Capillary electrophoresis and capillary electrochromatography of organic pollutants

Capillary electrophoresis (CE) has a unique capability for separation of analytes of environmental concern, particularly those that are more polar and ionic, based on the complementary separation principle of electrophoresis. In the past few years, CE has been selectively used to analyze various classes of compounds having current or potential environmental relevance. This review outlines the current status of CE for the determination of environmental pollutants, based predominantly on research results published from the beginning of 1997 to early 1999. Covered are environmental pollutants of all types except pesticides and inorganics. Certain naturally produced toxins are also covered because of their significant impacts upon human health and the environment. CE methods, as with all methods, must be judged on their ability to provide approaches that are reliable, sensitive, selective, and rapid, while meeting "green chemistry" initiatives for pollution prevention. We also compare CE methods to benchmark environmental techniques involving gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), and high performance liquid chromatography (HPLC).

Capillary electrochromatography with thermo-optical absorbance detection for the analysis of phenylthiohydantoin-amino acids

Capillary columns were packed with 3 microns C18 stationary phase, interfaced with an ultraviolet-laser based thermo-optical absorbance detector, and evaluated for separation of a mixture of phenylthiohydantoin-amino acids. These columns demonstrated consistent performance with a relative standard deviation (RSD) for migration time of less than 1.5% and a separation efficiency of 216,000 plates/m for the electroosmotic flow marker, thiourea. The thermo-optical absorbance detector was based on a 248 nm krypton-fluoride excimer laser. Detection limits (3 sigma) ranged from 1.6 to 4.8 x 10(-7) M phenylthiohydantoin (PTH)-amino acid injected onto the column, which is a factor of three superior to those obtained in micellar electrokinetic chromatographic analysis of these compounds. A mixture of 17 PTH amino acids was injected onto the capillary; 13 components were nearly baseline resolved in 14 min.