Determination Of Carbon Dioxide Concentrations Research Articles

Determination of Carbon Dioxide Concentration in CO2 Supplemental Greenhouse for Tomato Cultivation during Winter and Spring Seasons

Determination of Carbon Dioxide Concentration in CO2 Supplemental Greenhouse for Tomato Cultivation during Winter and Spring Seasons

The Determination of Carbon Dioxide Concentration Using Atmospheric Pressure Ionization Mass Spectrometry/Isotopic Dilution and Errors in Concentration Measurements Caused by Dryers

An atmospheric pressure ionization mass spectrometry/isotopically labeled standard (APIMS/ILS) method has been developed for the determination of carbon dioxide (CO(2)) concentration. Descriptions of the instrumental components, the ionization chemistry, and the statistics associated with the analytical method are provided. This method represents an alternative to the nondispersive infrared (NDIR) technique, which is currently used in the atmospheric community to determine atmospheric CO(2) concentrations. The APIMS/ILS and NDIR methods exhibit a decreased sensitivity for CO(2) in the presence of water vapor. Therefore, dryers such as a nafion dryer are used to remove water before detection. The APIMS/ILS method measures mixing ratios and demonstrates linearity and range in the presence or absence of a dryer. The NDIR technique, on the other hand, measures molar concentrations. The second half of this paper describes errors in molar concentration measurements that are caused by drying. An equation describing the errors was derived from the ideal gas law, the conservation of mass, and Dalton's Law. The purpose of this derivation was to quantify errors in the NDIR technique that are caused by drying. Laboratory experiments were conducted to verify the errors created solely by the dryer in CO(2) concentration measurements post-dryer. The laboratory experiments verified the theoretically predicted errors in the derived equations. There are numerous references in the literature that describe the use of a dryer in conjunction with the NDIR technique. However, these references do not address the errors that are caused by drying.

A simple approach to validation of directed‐flow nose‐only inhalation chambers

Directed-flow nose-only exposure systems are designed and operated so that the genuine test atmosphere is dynamically delivered to each exposure port and exhaled air from exposed animals is immediately exhausted without the possibility of other animals rebreathing this atmosphere. This technique is particularly useful for preventing uncontrolled changes of exposure atmospheres, stimulating breathing activity due to the rebreathing of exhaled carbon dioxide, and the conserving a test material that is available only in limited quantities. The intricate relationship of the delivered flow of air at each exposure port relative to the respiratory minute volume of the exposed animal appears to be critical for the state-of-the-art performance of directed-flow nose-only exposure systems. This analysis revealed that the determination of carbon dioxide concentrations at different inhalation chamber locations, including exposure ports, is a simple and cost-effective procedure to evaluate whether the rebreathing of atmospheres can be excluded. It has been shown that directed-flow systems need to be operated at an exposure air flow rate greater than 2.5 times the respiratory minute volume of the exposed animal or optimally approximately 0.75 l min(-1) per rat exposure port ( approximately 3.75 times the minute volume of young adult rats) to prevent higher CO(2)-concentrations occurring.

Biofiltration of waste gases with the fungi Exophiala oligosperma and Paecilomyces variotii

Two biofilters fed toluene-polluted air were inoculated with new fungal isolates of either Exophiala oligosperma or Paecilomyces variotii, while a third bioreactor was inoculated with a defined consortium composed of both fungi and a co-culture of a Pseudomonas strain and a Bacillus strain. Elimination capacities of 77 g m(-3) h(-1) and 55 g m(-3) h(-1) were reached in the fungal biofilters (with removal efficiencies exceeding 99%) in the case of, respectively, E. oligosperma and Paecilomyces variotii when feeding air with a relative humidity (RH) of 85%. The inoculated fungal strains remained the single dominant populations throughout the experiment. Conversely, in the biofilter inoculated with the bacterial-fungal consortium, the bacteria were gradually overgrown by the fungi, reaching a maximum elimination capacity around 77 g m(-3) h(-1). Determination of carbon dioxide concentrations both in batch assays and in biofiltration studies suggested the near complete mineralization of toluene. The non-linear toluene removal along the height of the biofilters resulted in local elimination capacities of up to 170 g m(-3) h(-1) and 94 g m(-3) h(-1) in the reactors inoculated, respectively, with E. oligosperma and P. variotii. Further studies with the most efficient strain, E. oligosperma, showed that the performance was highly dependent on the RH of the air and the pH of the nutrient solution. At a constant 85% RH, the maximum elimination capacity either dropped to 48.7 g m(-3) h(-1) or increased to 95.6 g m(-3) h(-1), respectively, when modifying the pH of the nutrient solution from 5.9 to either 4.5 or 7.5. The optimal conditions were 100% RH and pH 7.5, which allowed a maximum elimination capacity of 164.4 g m(-3) h(-1) under steady-state conditions, with near-complete toluene degradation.

Determination of carbon dioxide concentration in water by use of gas chromatography

Determination of carbon dioxide concentration in water by use of gas chromatography

A new portable CO 2 gas analyser and its use in field measurements

A simple, portable instrument for the determination of carbon dioxide concentration in atmospheric air by non-aqueous titration is described. The method can be used in the range 10–10,000 p.p.m. 50-ml air samples containing about 300 p.p.m. CO 2 can be analyzed with an accuracy of ± 3%. With increasing sample size the accuracy increases. A simple device is used to compensate for the influence of temperature and pressure. The time required for one titration is about 2 min.

A Gasometric Apparatus for Direct Reading Determination of Carbon Dioxide Concentration in Gas Mixtures

A Gasometric Apparatus for Direct Reading Determination of Carbon Dioxide Concentration in Gas Mixtures