Ionic liquids as solvents for in situ dispersive liquid–liquid microextraction of DNA

Six ionic liquids (ILs) were applied for the first time as solvents in the extraction and preconcentration of deoxyribonucleic acid (DNA) using an in situ dispersive liquid–liquid microextraction (DLLME) approach. The effect of different IL substituents and functional group on the extraction efficiency of DNA was investigated. The highest extraction efficiencies of DNA were obtained using 1-(1,2-dihydroxypropyl)-3-hexadecylimidazolium bromide (C16POHIM-Br) and N,N-didecyl-N-methyl-d-glucaminium bromide [(C10)2NMDG-Br]. Extraction efficiencies higher than 97% were obtained using small amounts of IL (0.50 mg) for each extraction. The extraction of DNA from a sample matrix containing metal ions and protein revealed that the metal ions did not interfere with the extraction of DNA and that the co-extraction of protein can be mitigated by performing the extraction under moderately acidic conditions. Data from 31P NMR spectroscopy suggest that a combination of electrostatic and π–π interactions dominate IL–DNA complexation and that the extraction is concentration dependant.