Improved model of the pulsed electron capture detector

Gobby, P. L.; Grimsrud, E. P.; Warden, S. W.

doi:10.1021/ac50053a023

Cited by 59 publications

(30 citation statements)

References 20 publications

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“…At the Adrigole and Barbados stations, constant frequency (4 kHz) electronics have been used to process the signal outputs from the "S" channel detector. Although the signal is slightly noisier by this method, it is potentially an absolute method of analysis where the coulometric reaction of halocarbons and electrons can be used to calculate halocarbon concentrations within the detector [Lovelock and Watson, 1978;Grirnsrud and Kirn, 1979;Gobby et al, 1980]. Also, since halocarbon measurements had been made at the Adrigole station commencing in 1970 by using the constant frequency electronics [Pack et al, 1977], it was desirable to continue with this method to maintain continuity in this long time series of measurements.…”

Section: Instrumentationmentioning

confidence: 76%

The Atmospheric Lifetime Experiment: 1. Introduction, instrumentation, and overview

Prinn¹,

Simmonds²,

Rasmussen³

et al. 1983

J. Geophys. Res.

134

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The Atmospheric Lifetime Experiment is designed to determine accurately the atmospheric concentrations of the four halocarbons CFCl3, CF2Cl2, CCl4, and CH3CCl3, and also of N2O with emphasis on measurement of their long‐term trends in the atmosphere. Comparison of these concentrations and trends for the four halocarbons with estimates of their industrial emission rates then enables calculations of their global circulation rates and globally averaged atmospheric lifetimes. The experiment utilizes automated dual‐column electron‐capture gas chromatographs which sample the background air about 4 times daily at the following globally distributed sites: Adrigole, Ireland (52°N, 10°W); Cape Meares, Oregon (45°N, 124°W); Ragged Point, Barbados (13°N, 59°W); Point Matatula, American Samoa (14°S, 171°W); and Cape Grim, Tasmania (41°S, 145°E). We review the climatology of these “clean air” sites and their ability to describe the global air mass. The instrumentation and methods for data acquisition and processing are then described. An overview of the data obtained and the trends derived during the 3‐year period from July 1978 through June 1981 for each of the five species being measured is presented. The comparative behavior of the species with latitude and time is emphasized. The global average surface concentrations of CFCl3, CF2Cl2, CH3CCl3, CCl4, and N2O are increasing at annually averaged rates of 5.7, 6.0, 8.7, 1.8, and 0.2% per year, respectively, at the midpoint of the 3‐year period of the measurements.

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Section: Instrumentationmentioning

confidence: 76%

The Atmospheric Lifetime Experiment: 1. Introduction, instrumentation, and overview

Prinn¹,

Simmonds²,

Rasmussen³

et al. 1983

J. Geophys. Res.

134

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“…At increasing ion densities in the bipolar (ions of both polaritie s present) ion source , diffusion first becomes ambipolar [13]) and is then replaced by ion-ion (or ion-electron) recombination as the main ion loss mechanism (recombination-dominated loss). This is the situation when 63Ni causes the ionization, as in the ECD [14] and in some API [15] and IMS sources [11]. Models of recombination-dominated ion sources have been published [16,17].…”

mentioning

confidence: 99%

“…The electric field within the source is then determined mainly by the space charge, and ion drift to the walls is the dominating ion loss mechanism . This is the case, for example, in the ECD directly after the electron-extraction pulse has been applied to the anode [14].…”

mentioning

confidence: 99%

Space-charge-dominated mass spectrometry ion sources: Modeling and sensitivity

Busman

Sunner

Vogel

1991

J. Am. Soc. Mass Spectrom.

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The factors determining the sensitivity of space-charge-dominated (SCD) unipolar ion sources, such as electrospray (ESP) and corona atmospheric pressure ionization (API) have been studied theoretically. The most important parameters are the ion density and ion drift time in the vicinity of the sampling orifice. These are obtained by solving a system of differential equations, "the space-charge problem." For some simple geometries, analytical solutions are known. For a more realistic "needle-in-can" geometry, a solution to the space-charge problem was obtained using a finite-element method. The results illustrate some general characteristics of SCD ion sources. It is shown that for typical operating conditions the minimum voltage required to overcome the space-charge effect in corona API or ESP ion sources constitutes a dominant or significant fraction of total applied voltage. Further, the electric field and the ion density in the region of the ion-sampling orifice as well as the ion residence time in the source are determined mainly by the space charge. Finally, absolute sensitivities of corona API ion sources were calculated by using a geometry-independent treatment of space charge.

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“…7. Thus, we implemented the well-known pulsed collector voltage mode in order to improve the linear range of the detector response (Maggs et al, 1971;E13 Committee, 2011;Gobby et al, 1980;Zlatkis and Poole, 1981). In pulsed mode, the electrons are mainly generated under field-free conditions in the reaction region, while the analyte molecules react with the electrons and the analyte ions are removed within the gas stream.…”

Section: Implementation Of the Pulsed Modementioning

confidence: 99%

Electron capture detector based on a non-radioactive electron source: operating parameters vs. analytical performance

Bunert

Kirk

Oermann

et al. 2017

J. Sens. Sens. Syst.

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Abstract. Gas chromatographs with electron capture detectors are widely used for the analysis of electron affine substances such as pesticides or chlorofluorocarbons. With detection limits in the low ppt v range, electron capture detectors are the most sensitive detectors available for such compounds. Based on their operating principle, they require free electrons at atmospheric pressure, which are usually generated by a β − decay. However, the use of radioactive materials leads to regulatory restrictions regarding purchase, operation, and disposal. Here, we present a novel electron capture detector based on a non-radioactive electron source that shows similar detection limits compared to radioactive detectors but that is not subject to these limitations and offers further advantages such as adjustable electron densities and energies. In this work we show first experimental results using 1,1,2-trichloroethane and sevoflurane, and investigate the effect of several operating parameters on the analytical performance of this new non-radioactive electron capture detector (ECD).

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Improved model of the pulsed electron capture detector

Cited by 59 publications

References 20 publications

The Atmospheric Lifetime Experiment: 1. Introduction, instrumentation, and overview

The Atmospheric Lifetime Experiment: 1. Introduction, instrumentation, and overview

Space-charge-dominated mass spectrometry ion sources: Modeling and sensitivity

Electron capture detector based on a non-radioactive electron source: operating parameters vs. analytical performance

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