18 February / March 2016
Mixing Water and Gas: The Quantitative Measurement of Water by Gas Chromatography Using Ionic Liquid Capillary Columns
by Leonard M. Sidisky, Gustavo Serrano, James L. Desorcie, Katherine K. Stenerson, Greg Baney, Michael Halpenny and Michael D. Buchanan MilliporeSigma, 595 N. Harrison Road, Bellefonte, PA 16823, USA
The determination of water content in solvents, alcoholic beverages and various consumer products such as foods, pharmaceuticals, fuels, and petroleum products is one of the most common types of chemical testing. Many techniques such as gravimetric analysis, Karl Fischer Titration, near infra-red spectroscopy, gas chromatography (GC) and others have been used for water quantification with good results [1]. However, the limitations of these approaches can include high limits of detection, large sample sizes required for trace analysis, side reactions, the use of expensive consumables, and the production of chemical waste. Previous work by Professor Daniel Armstrong and co-workers has described the use of ionic liquid GC capillary columns for the trace analysis of the water content in a wide variety of solvents [2]. These columns were capable of providing a rapid and quantitative determination of water content using very small sample amounts. This paper further examines the characteristics of ionic liquid capillary columns for the GC measurement of water.
Ionic liquid stationary phases have been discussed in a series of papers over the years describing the unique selectivity and ability to tune the properties of the phases for a number of different applications [3, 4, 5, 6, 7]. Presently, a series of three ionic liquid capillary GC columns of different selectivities are characterised by their ability to produce a sharp peak shape for water and other small polar analytes. The water peak produced by these columns is sharp enough to allow for proper integration and subsequent quantitation. Due to the high polarity of the ionic liquid stationary phases, water also does not interfere chromatographically with the analysis of many other small aliphatic and polar analytes. The three phase chemistries of these columns are available under the names WatercolTM WatercolTM
1460, WatercolTM 1900 and
1910. Figure 1 shows the structure of each of the chemistries. The composition of all three phases demonstrates the unique combinations of cations and anions that can be used to prepare ionic liquid phases. The WatercolTM
1460 phase
is tricationic phosphonium based, while the WatercolTM
1900 and WatercolTM 1910
phases are both dicationic imidazolium based with differing pendant groups. These pendant groups contribute to the
Figure 1: Structures of Watercol Phases WatercolTM 1460 - Tri(tripropylphosphoniumhexamido) triethylamine trifluoromethanesulfonate
WatercolTM
1900 – 1, 11 Di(3-methylimidazolium) 3,6,9 trioxaundecane trifluoromethanesulfonate
WatercolTM
1910- 1,11-Di(3-hydroxyethylmidazolium) 3,6,9-trioxaundecane trifluoromethanesulfonate
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60
