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Analytical Instrumentation of low-level benzene peaks. Figure 6 shows a chromatogram run on this system of
a standard mixture prepared using ethanol as the solvent. In this case even though the ethanol comprises more than 95% of the sample, there is very little interference between its chromatographic peak and that of benzene at a concentration of 0.05% (the lowest calibration concentration).
Conclusions
• The combination of modern capillary columns with the Swafer technology has taken a mature method and improved the quality of the data and reduced the run time significantly.
• Baseline separation of ethanol, benzene, toluene and the 2-butanol internal standard has been demonstrated.
• Even though the method relies on significant carrier gas pressure and flow rate changes, the quantitative and peak retention time precisions are excellent.
• The chromatographic run time has been reduced from about 8 minutes for the original method (or 16 minutes for some revised column sets) to just 4 minutes. The total cycle time of the chromatographic analysis (including pressure equilibration) is 5.4 minutes enabling 88 samples to be analysed during an 8-hour working shift.
Figure 6: Chromatogram of standard mixture containing 0.05% v/v benzene and 0.5% v/v toluene in pure ethanol with added internal standard
This excellent result is due to many factors: the efficient rinsing of the autosampler syringe, the injector flowpath and the efficiency of the backflush process in removing the bulk of the sample form the system
As mentioned in the introduction, one of the big
challenges with the existing D-3606 method is dealing with the presence of large concentrations of ethanol in modern gasolines. The ethanol peak elutes in front of the benzene peak. On packed columns, the ethanol peak will tail and start to interfere with the digital integration
• The method is able to analyse samples with low levels of benzene in the presence of high levels of ethanol.
Programmable Viscometer for Multi-products References
Sofraser (France) is pleased to announce the availability of the 9602 processor, its new model of 9600 series. The new 9602 model manages applications handling up to 8 different products owing to its 8 selectable parameters settings.
Owing to its LCD display and user-friendly menu it is an easy job to configure the sets of parameters for each different product and switch rapidly from one to the others at the beginning of a new batch.
For each product, setting parameters enable end-user to customise viscosity unit (Pa.s, mPa.s, P, cP, cSt), viscosity correlation (cup seconds, concentration, dry extract, …), alarm limits, current outputs limits, reference temperature and data for viscosity calculation at reference temperature. Product selection can also be performed by logic signals.
Matched with Sofraser MIVI process
sensor, 9602 viscosity processor is the reply for viscosity measures from 0.01mPa.s to 1,000,000mPa.s, -40°C to 300°C, vacuum to 500bar, in sanitary or hazardous environments.
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ASTM Approves Column Set
Flash RGA
Full Refinery Gas Analysis in 200 seconds! UOP 539, DIN 51666, ASTM D2163 Proven technology: robust and reliable 19” rack mounted, fully digital
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Labs testing ethanol-containing finished gasolines now have a better alternative to TCEP columns—at its recent meeting, the ASTM D02 Committee announced a revision to method D3606 which now includes the D3606 column set from Restek (USA). This column set separates benzene from ethanol completely and much more reliably than TCEP columns, resulting in more accurate quantification and tighter process control. Since a third column is not required, use of this column set simplifies installation and analysis. Additionally, all D3606 column sets are tested for method applicability and have higher thermal stability than TCEP columns, resulting in longer column lifetimes.
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