Chemistry Reference
In-Depth Information
substitutes. ILs are liquid at ambient temperature, and are usually composed of relatively large organic cations
and inorganic anions. They have negligible vapor pressure, good thermal stability, tunable viscosity, and
primarily anion-dependent miscibility with water as well as various organic solvents. Because of these unique
characteristic properties, ILs have been widely used in many research fields, and separation science is no
exception.
Jiang
et al
. used 1-butyl-3-methylimidazolium tetrafluoroborate to test residual solvents in pharmaceutical
preparations with static headspace gas chromatography [60]. The purpose of their work was to demonstrate
the feasibility of ILs as diluents. Six solvent (acetonitrile, dichloromethane,
N
-methyl-2-pyrrolidone, toluene,
N,N
-dimethylformamide and
n
-butyl ether) were dissolved in ILs. The method of an external standard was
used for quantitative analysis. Its performance was evaluated and validated, and all of the relative standard
deviations were lower than 10
; the limits of detection were all of the ppm level. The developed method was
both accurate and linear, and better sensitivities for the six solvents were gained with IL as diluent compared
with DMSO, which is conventionally used.
Liu
et al
. used 1-butyl-3-methylimidazolium chloride/salt-based aqueous two-phase systems as a simple,
rapid and effective sample pretreatment technique coupled with HPLC, for the analysis of the major opium
alkaloids in
P. papaveris
[61]. To find the optimal conditions, various factors were investigated systematically;
the results indicated that both the pH value and the salting-out ability of salt had a great influence on the phase
separation. The recoveries of codeine and papaverine were 90.0-100.2
%
respectively.
Compared with the conventional polymer-salt-water system, the extraction efficiencies obtained from the
developed method were stable in a wide temperature range. In addition, this system had a relatively lower
viscosity, and was convenient to be coupled with HPLC. This ILs technique was less time-consuming, and
used nonvolatile solvents, which were to be distinct advantages over the conventional solid-phase extraction.
The developed method was proved highly efficient and fast for the separation and enrichment of hydrophobic
drug in biological samples, and would be a great potential in coupling other instruments, such as flow-
injection analysis and capillary electrophoresis.
%
and 99.3-102.0
%
20.12
The future in green bioanalysis
The development of green bioseparation methods is indispensable to improve the problem of the exhaustion
of fossil fuel resources and global environmental problems. Using an aqueous solution instead of organic
solvents, in parts of these serious problems may be improved. There have been developed promising analytical
methods that were introduced in this article. Environmental-responsive chromatography, which utilizes an
intelligent polymer as the stationary phase, and uses only water as the mobile phase is one excellent example.
This method has been applied to the separation of biologically active molecules, such as pharmaceutical
agents, bioactive peptides and biomacromolecules (proteins). It is expected that various novel environmental-
friendly methodologies can be accomplished by combining a number of green analytical methods, and can be
applied to many research fields, such as medical and pharmaceutical sciences, biological science and
environmental science.
References
1. Brown, P.R. and Grushka E. (eds) (2001)
Advances in Chromatography 41
, Marcel Dekker, New York.
2. Brettschneider, F.; Jankowski, V.; Günthner, T.; Salem, S.; Nierhaus, M.; Schulz, A.; Zidek, W. and Jankowski, J.
(2010) Replacement of acetonitrile by ethanol as solvent in reversed phase chromatography of biomolecules,
J. Chromatogr. B
.,
878
, 763-768.
