Analytical Instrumentation The analysis of impurities in propylene on an Rt®
Good peak separation simplifies quantification of impurities in propylene.
-
Alumina BOND (Na2SO4) column is shown in Figure 3. Sharp, symmetric peaks are obtained for all
compounds, allowing challenging separations, such as trace levels of cyclopropane from propylene, to be achieved. These columns have high loadability, as demonstrated by the minimal tailing of the propylene peak. Good separation of propadiene and acetylene from n-butane is also observed and can be further increased by lowering elution temperatures. Excellent peak shape is also obtained when using an Rt®
-Alumina BOND (KCl) column for the analysis of impurities in ethylene, as shown in Figure 4. Here, the column is coupled to an Rtx®
-1 column, as prescribed
in ASTM Method D6159, to ensure complete resolution of all compounds. Once again, excellent peak symmetry is obtained, illustrating the high loadability of the column and predictability of retention times. The excellent peak shape and separation seen in both applications illustrates the quality of the deactivations; since column reactivity is minimised, responses for polar unsaturates, such as dienes, are optimised.
Figure 3: Rt® -Alumina BOND/Na2SO4 columns exhibit high loadability and ensure reliable separation of impurities in propylene. Column: Rt®
-Alumina BOND/Na2SO4 (50 m x 0.53 mm x 10.0 µm); Sample: propylene and C1-C5 hydrocarbons; Inj.: 10 µm split, 35 mL/min. split vent flow rate; Inj. temp.: 200 °C; Carrier gas: He, 68.9 kPa; Linear velocity: 47 cm/sec. @ 50 °C; Oven: 50 °C to 150 °C
at 6 °C/min.; Det.: FID @ 200 °C; Peaks: 1) methane, 2) ethane, 3) ethylene, 4) propane, 5) cyclopropane, 6) propylene, 7) isobutane, 8) n-butane, 9) propadiene, 10) acetylene, 11) trans-2-butene, 12) 1-butene, 13) isobutylene, 14) cis-2-butene, 15) isopentane, 16) n-pentane, 17) 1,3-butadiene, 18) methyl acetylene.
17
Conclusion
High loadability ensures accurate ethylene testing results.
-Alumina BOND PLOT columns offers petrochemical labs the opportunity to obtain more reliable results in less time for major products such as ethylene and propylene.
Poor reproducibility for flow and retent- ion is a widely-recognised problem with alumina PLOT columns, as inconsistent flow characteristics cause retention times to vary significantly between columns. Restek’s new PLOT column manufacturing process provides tight control of the column coating process and, as a result, highly reprod- ucible column flows are achieved. Ultimately, the superior technology used to produce Rt®
Restek is a leading developer and manufacturer of chromatography columns and accessories.
Figure 4: Excellent peak symmetry for ethylene and related impurities is obtained on Rt® retention times and high loadability.
-Alumina BOND/KCl columns, resulting in stable
Column: Rt(r)-Alumina BOND/KCl (50 m x 0.53 mm x 10.0 µm) in series with Rtx(r)-1 (30 m x 0.53 mm x 5.0 µm); Sample: ethylene and C1-C5 hydrocarbons; Inj.: 1 µm split, 60 mL/min. split vent flow rate; Inj. temp.: 200 °C; Carrier gas: He, 55.2 kPa; Linear velocity: 25.4
cm/sec. @ 35 °C; Oven: 35 °C (hold 2 min.) to 190 °C at 4 °C/min. (hold 15 min.); Det.: FID @ 200 °C; Peaks: 1) methane, 2) ethane, 3) ethylene, 4) propane, 5) cyclopropane, 6) propylene, 7) acetylene, 8) isobutane, 9) propadiene, 10) n-butane, 11) trans-2-butene, 12) 1-butene, 13) isobutylene, 14) cis-2-butene,15) isopentane, 16) methyl acetylene, 17) n-pentane, 18) 1,3-butadiene.
We provide analysts around the world with the innovative tools they need to monitor the quality of air, water, soil, foods, pharmaceuticals, chemical, and petroleum products.
Improved Version of Award Winning Connection Device for GC Capillary Columns
Since the launch of the Meltfit One in January 2008, Nlisis Chromatography (The Netherlands) has collected valuable feedback from users throughout the world. Based on these data, Nlisis has announced a new release of the award-winning connection device for capillary columns in GC. The new Meltfit One has an improved performance and usability. Among other things, the new release of the Meltfit One has a battery on board which enables users to make up to 40 connections without having to recharge. In addition, the Meltfit One has become completely portable, since an integral air source has been incorporated in the device, negating the need to have an external air supply nearby. Finally, an new version of the software has been developed, offering more useful functions. Having made these changes NLISIS can fully guarantee that connections made with the proprietary Meltfit glass tubes are always leak tight.
The petrochemical industry is an important market for Nlisis. Shell and ExxonMobil were among the first companies to take advantage of this innovative connection technology. Marketing manager Paul Heere comments: ”In the petrochemical industry in particular time equals money. Time spent preparing samples and carrying out sample analysis is wasted if a bad column connection ruins the results. This is particularly true when you take into consideration the wide use of GC/MS and GC x GC in this industry. The Meltfit One removes the worry associated with leaking connections and therefore saves valuable time and money as well as improving the chromatography.”
Reader Reply Card No 45
February/March 2010
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