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Chromatographic Methods
Published in Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus, Environmental Chemical Analysis, 2018
Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus
When the sample to be injected is a gas, a gas sampling valve is often used to inject a measured portion into the column. This valve contains a loop of known volume which is filled in the “load position” by allowing the sample gas to flow through it. When the valve is turned to the “inject position,” the carrier gas is diverted through the loop, and the sample is carried onto the column. In Figure 4.9, we can see that the carrier gas always flows to the column, irrespective of whether the valve is in the load or inject position. The sample size is usually changed by installing a different sized loop, although, if a pressure gauge is mounted on the system, the sample pressure may be changed to change the amount injected. Since the sample is a gas, the temperature of the loop will also make a difference, if it is subject to wide variations.
Sampling and Collection of Particulate Matter For Analysis
Published in Thomas A. Barber, Control of Particulate Matter Contamination in Healthcare Manufacturing, 1999
Precleaned bottles or other containers cleaned as described earlier in this chapter can also be used for sampling fluid lines. These systems should be operated for several minutes before taking the sample. This ensures that contaminants are evenly distributed throughout the system. The following procedure is used: With the system operating, open the sampling valve and allow sufficient liquid to flow into a waste container to flush out the valve. The sample must never be taken while the sampling valve is first being opened.Remove the cap from the sample bottle and hold it in a free hand.Immediately place the bottle into the liquid stream and collect the desired volume. Do not “rinse” the container in the sample fluid prior to collection.Remove the container and replace the plastic film and cap.Label the container.Turn off the sampling valve after removing the bottle.Avoid wiping the sampling valve or the neck of the bottle with a cloth or paper towel, since this may introduce fibers into the sample.The sample bottle should be returned to the laboratory promptly for filtration and analysis.
Application Examples
Published in Anders Andersson, Measurement Technology for Process Automation, 2017
Make sure that products are well mixed. If needed, install a static mixer, a device that starts a rotation in the pipe which helps to mix the product. Product quality can be more difficult to check when the process is constantly running, and therefore a sampling valve is useful.
In situ field method for evaluating biodegradation potential of BTEX by indigenous heterotrophic denitrifying microorganisms in a BTEX-contaminated fractured-rock aquifer
Published in Environmental Technology, 2021
Kyungjin Han, Uijeon Hong, Sunhwa Park, Sooyoul Kwon, Young Kim
To prepare a test solution, 1200 L of native groundwater was extracted, and then purged with nitrogen gas for 3 h at a rate of 1 L/min to remove DO. During the 1st WWT, KBr and NaNO3 were added to the test solution to final concentrations of 13.8 ± 0.37 mmol Br−/L and 23.8 ± 0.48 mmol N/L, respectively. The prepared test solution was injected through the intervals of upper (12.3 m below ground surface) and lower (28.3 m below ground surface) packers of BH-8 at a rate of 4.5 L/min. The injection solution was purged continuously with nitrogen gas during the injection phase to maintain its anoxic condition. The composition of the test solution was monitored during injection by collecting samples from a sampling valve. Over 12 days, periodic sampling of the test solution/groundwater mixture from two wells (BH-8 and BH-4) was used to evaluate relative anaerobic degradation potential of each BTEX and dissimilative NO3− utilization. The 2nd WWT was similarly performed as described above.
Biochemical methane potential of residual biomass for energy generation
Published in Environmental Technology, 2021
U. Galván-Arzola, C. U. Moreno-Medina, R. Lucho-Chigo, M. D. J. Rodríguez-Rosales, R. Valencia-Vázquez
Biogas volume production was measured every two days by the displacement method according to the methodology proposed by Parajuli [10]. The displacement system was composed by two clear plastic containers: one container, hermetically sealed, was filled with acidified water (pH < 1.7) and the second container was used to receive the displaced liquid. The plastic containers (1 L) were adapted with fittings and a sampling valve each reactor. The displacement water was acidified distilled water with sulfuric acid (pH values < 1.7) in order to avoid that carbon dioxide present in the biogas was dissolved into the liquid phase, thus giving an incorrect volume and quality values. Liquid displaced was measured with graduated probes of different sizes in order to reduce the measurement error. The concentration of methane (%CH4), carbon dioxide (%CO2), oxygen (%O2) and other gases (%BAL) present in the biogas was determined every two days using a portable electrochemical cell biogas analyser (Landtec Biogas-Check5000). The biogas sampling system was made of high-pressure hoses with a one-way water filter 0.20 μm Midisart 2000 and chemical filter packaged for removal of hydrogen sulfide. Additionally, a gas-check valve was installed to prevent air intrusion during the biogas measurement and re-filling of displaced water.
Comparison of methanol to gasoline conversion in one-step, two-step, and cascade mode in the presence of H-ZSM-5 zeolite
Published in International Journal of Sustainable Energy, 2018
Valentin Yu. Doluda, Antonina A. Stepacheva, Natalia V. Lakina, Oleg V. Manaenkov, Vladimir P. Molchanov, Galina N. Demidenko, Valentina G. Matveeva, Viktor I. Panfilov, Mikhail G. Sulman, Esther M. Sulman
In order to analyse the reaction mixture composition (hydrocarbons, methanol, DME, CO, CO2, H2, N2), the state-of-the-art analytic complex including gaseous chromatograph (Crystall 2000M, MetaChrom, Russia) equipped with flame ionisation detector and thermal conductivity detector was used. The reaction mixture was directly injected into the chromatograph using automatic sampling valve with the volume of 0.25 mL. The chromatographic analysis was provided under the following conditions: evaporator temperature was 270°C; the consumption of gas-carrier (helium) 30 mL/min; gas-carrier pressure 0.35 MPa; duration of the analysis was 30 min; packed column 2.5 m × 3 mm filled with Haesep Q adsorbent with the fraction of 80/100 mesh; initial column temperature 40°С was held for 4 min; then the column was heated to 250°С with the rate of 15°С/min and maintained at this temperature for 12 min, temperature of the detectors was 260°C. To determine the composition of the gas mixture, the method of absolute concentrations was used. The accuracy of the analysis was increased using Clapeyron-Mendeleev equation, operating pressure and the ambient temperature were recorded, and recalculation to standard conditions was performed. Prior to the injection, the gas syringe was purged three times with the analysed gas.