Ionic liquids as tunable materials in (bio)analytical chemistry
Ionic liquids as tunable materials in (bio)analytical chemistry
Jared L. Anderson 0
Kevin D. Clark 0
0 Department of Chemistry, Iowa State University , 1605 Gilman Hall, Ames, IA 50011 , USA
1 Jared L. Anderson
Ionic liquids (IL) are a unique class of non-molecular ionic solvents that possess a multitude of customizable properties. They are often composed of bulky and asymmetric nitrogen or phosphorus-containing cations paired with organic or inorganic counter anions. One of the most remarkable features of ILs that makes them so intensely studied is their low melting points, allowing many of them to be liquids at room temperature. This is usually accomplished by imparting asymmetry into the cation, thereby preventing the cations and anions from undergoing packing into a crystalline form. In addition, ILs possess a number of other interesting and useful physicochemical properties including extremely low vapor pressures at ambient temperatures, high thermal stabilities, wide liquid ranges, tunable viscosity, and high conductivity. In addition, ILs can be designed to possess varied solubility in water and many organic solvents, opening up a plethora of opportunities for their use in many diverse areas of research. It has been very interesting to observe the field of ILs grow into the highly interdisciplinary field that it is today. The origin of the first true Bionic liquid^ is a bit controversial, but likely dates back to the late 1800s. Many of the early compounds were high-temperature molten salts followed by inorganic and organic chloroaluminates, which became highly studied electrolytes within the electrochemistry community. Synthetic
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Published in the topical collection Ionic Liquids as Tunable Materials in
(Bio)Analytical Chemistry with guest editors Jared L. Anderson and
Kevin D. Clark
methods used to prepare the more commonly studied
water- and air-stable ILs were introduced in the 1980s.
These features, coupled with the aforementioned
advantageous properties of ILs, have led to their widespread
use in the field of green chemistry. Many of the early
IL studies were focused on understanding their effects
as solvents in chemical reactions, particularly in the
areas of catalysis and physical organic chemistry. As
this knowledge began to quickly accumulate, a greater
number of cations and anions were unveiled thereby
creating an even greater portfolio of possible ILs for
applications.
The highly unique and tunable physicochemical
properties of ILs have attracted significant attention from the
analytical chemistry community. This topical collection
of articles includes articles from not only the traditional
branches of analytical chemistry (i.e., spectroscopy,
electrochemistry, mass spectrometry, and separation science)
but also their growing use in emerging areas of
bioanalysis. Several of the articles within this topical
collection exploit magnetic ionic liquids (MILs) as either
a magnetoactive solvent in microextractions or as a
stationary phase in gas chromatography. MILs are a
subclass of ILs generated by the incorporation of
paramagnetic components into the IL structure. In addition to
possessing the tunable physicochemical properties of
conventional ILs, MILs exhibit a strong susceptibility
to external magnetic fields. The paramagnetic behavior
of MILs is attributed to unpaired electrons in the d or f
orbitals of the metal-based cation/anion. A number of the
articles within the topical collection examine ILs as
stationary phases in gas chromatography for the separation
of multi-component volatile compounds, water,
fragrances, and essential oils. In addition, IL stationary
phases are highlighted in the separation of fatty acid
methyl esters using two-dimensional gas chromatography
with solid-state modulation. In two mass spectrometry
articles, ILs are exploited as MALDI MS matrices for the
detection of bacterial communication molecules and
virulence factors and used as additives in paired ion
electrospray ionization mass spectrometry for the
sensitive determination of N-blocked amino acids. Several
articles discuss ILs and polymeric ionic liquids (PIL) as
extractionmedia in sample preparation. Two articles
within the topical collection involve electrochemical
applications of ILs with one exploring capacitive hysteresis at
the IL-polycrystalline gold interface and the other
exami n i n g s i g n a l d r i f t a n d c a l i b r a t i o n m e t h o d s w h e n
performing amperometric gas sensing in ILs. Another
article introduces a new solution phase and vapochromic
detection method for amines that is based on ILs. Finally,
a Trends article discusses the emerging role that ILs,
MILs, and PILs have in the analysis of biological
samples including proteins, peptides, and nucleic acids.
We would like to extend a tremendous amount of
appreciation to all authors who have contributed to this
topical collection. The highly diverse topics represented
within this topical collection clearly show the
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