Generation of gaseous standards using exponential dilution flasks in series

Greenhouse, S.; Andrawes, Fikry F.

doi:10.1016/s0003-2670(00)83315-2

Cited by 12 publications

(6 citation statements)

References 15 publications

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“…Recalling eq , C t ′ = C o exp(− t /τ d ), and considering that d V = q d t , the differential equation will be where τ = V / q is the time constant for the dilution flask and τ d is the time constant for the desorption process. This system is similar to the combination of two exponential dilution flasks in series, described by Greenhouse and Andrawes . In their design, the first flask was connected to a second flask so that a further exponential dilution took place.…”

Section: Results and Discussionmentioning

confidence: 99%

“…The output function of the desorption process in our model was exactly the same as that of the first dilution flask in the double dilution flask system, i.e., exponential decay. The solution for eq when the two time constants are different will be where τ df and τ des are the time constants for the dilution flask and the desorption processes, respectively. Rearrangement of eq results in where k 1 is the desorption rate constant and k 2 = k – k 1 , in which k is the dilution flask rate constant.…”

Section: Results and Discussionmentioning

confidence: 99%

“…This system is similar to the combination of two exponential dilution flasks in series, described by Greenhouse and Andrawes. 33 In their design, the first flask was connected to a second flask so that a further exponential dilution took place. The output function of the desorption process in our model was exactly the same as that of the first dilution flask in the double dilution flask system, i.e., exponential decay.…”

Section: Response To a Gaseous Single-step Functionmentioning

confidence: 99%

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Dynamic Response of Ion Mobility Spectrometry

Tabrizchi

Abadi

Parchami

et al. 2022

J. Am. Soc. Mass Spectrom.

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Ion mobility spectrometers (IMS) are widely used in the security industry as well as in analytical measurements. Nevertheless, the IMS input is dynamic in nature because the sampling input can vary over time. Similar to most instruments, IMS is unable to respond immediately to variations in the input sample. Therefore, the measurements are made under transient conditions, which may affect the results. This work investigates the dynamic response of an IMS to different inputs, including steps, pulsed, exponential, and Gaussian functions. A theoretical model was developed based on two phenomena: the accumulation or dilution of a sample in the ionization region and the adsorption or desorption inside the injection port. Both processes have a charging/discharging nature. Thus, a mathematical expression was derived that takes into account two RC circuits in series. Fitting the output signal of the experimental data to the expression obtained from the model gave reasonable time constants of 2–4 s and 15–20 s for the dilution and the desorption processes, respectively. The model performance was evaluated by comparing the output with the experimental results, which were in excellent correlation. IMS was also found to behave in a manner similar to a second-order instrument, in which the output is related to the input via a second-order differential equation. These results are applicable to GC-IMS and IMS-based detectors.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Section: Response To a Gaseous Single-step Functionmentioning

confidence: 99%

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Dynamic Response of Ion Mobility Spectrometry

Tabrizchi

Abadi

Parchami

et al. 2022

J. Am. Soc. Mass Spectrom.

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“…The exponential dilution flask, Figure 8.31(A), is a hybrid static/dynamic system [429][430][431]. The exponential dilution flask, Figure 8.31(A), is a hybrid static/dynamic system [429][430][431].…”

Section: Diffusionmentioning

confidence: 99%

Sample Preparation for Chromatographic Analysis

Poole

1991

Chromatography Today

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“…The two main methods for preparing gas reference mixtures are static or dynamic [16][17][18][19][20], although a specific method based on an exponential dilution also exists [21,22]. Of the analytical techniques devoted to gas analysis, gas chromatography [23][24][25][26][27] is still widely used due to its proven reliability and the possibility of integrating different type of detector depending on the compound family or the concentration range studied.…”

Section: Introductionmentioning

confidence: 99%

A simple method for the preparation and injection of gas mixtures into a gas chromatograph using a two-component device

Donval

Guyader

Boissy

2020

Journal of Chromatography A

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Environmental sciences are expanding and are based on standardized and certified calibrations when measurements are required. When a gaseous composition is quantified, commercial standards are used. Here, we report on a two-component device for the preparation and injection of gas mixtures at the appropriate levels of pressure and volume. The two-component calibrator/injector can be used simultaneously or separately depending on the experimental objective but their combination is extremely effective for injecting gas mixtures at low concentrations. The quantity of gas introduced into a gas chromatograph with the injector can be adapted to the sensitivity of the detector or to avoid column overload. The calibrator provides for a large range of gas-mixture concentrations, from ppm to % mol/mol with an error of preparation of around 1% and an accuracy of less than 3%. This device prepares a variety of gas mixtures (hydrogen, methane and dioxide of carbon) which are compared with certified mixtures by means of gas chromatographic measurements. The results show good agreement between prepared and certified mixtures with a maximum difference of 2% which remains within the relative error of commercial stanard. In addition, the preparation of dissolved methane at different concentrations in seawater is presented as a direct application of the calibrator. Highlights► Description of a device for injecting gas mixtures (gas injector). ► Description of a device for preparing gas mixtures (gas calibrator). ► Application of gas calibrator for preparation of H2, CH4 and CO2 mixtures: comparison with certified mixtures. ► Application of gas calibrator to enrich seawater with CH4.

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Generation of gaseous standards using exponential dilution flasks in series

Cited by 12 publications

References 15 publications

Dynamic Response of Ion Mobility Spectrometry

Dynamic Response of Ion Mobility Spectrometry

Sample Preparation for Chromatographic Analysis

A simple method for the preparation and injection of gas mixtures into a gas chromatograph using a two-component device

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