Calculation to Relative Molar Response Factors of Thermal Conductivity Detectors in Gas Chromatography.

Hoffmann, E. G.

doi:10.1021/ac60190a010

Cited by 25 publications

(2 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As C S of acetone is with 542 K very high (Hoffmann, 1962), µ roughly scales with T 3/2 . Therefore, the temperature dependence of the viscous flow can be expressed as:…”

Section: Viscous Flow (Large Pores)mentioning

confidence: 96%

An unheated permeation device for calibrating atmospheric VOC measurements

Brito

Zahn

2011

Atmos. Meas. Tech.

View full text Add to dashboard Cite

Abstract. The development of an unpowered permeation device for continuous calibration of in-situ instruments measuring atmospheric volatile organic compounds (VOCs) is described. Being lightweight and compact, and containing only negligible amounts of chemicals, the device is especially suited for field use such as on board aircraft. Its speciality is to maintain the permeation process in thermal equilibrium, so that the instantaneous permeation rate can be ascribed to a simple temperature measurement. This equilibrium state is maintained by a combination of three features: (i) a thin PTFE membrane as permeation medium which guarantees short stabilization times, (ii) a water bath as heat buffer, and (iii) a vacuum-panel based insulation, in which features (ii) and (iii) minimize temperature drifts to ∼30 mK h −1 per Kelvin temperature difference to the environment. The respective uncertainty of the permeation rate due to thermal non-equilibrium is kept below 1 %. An extensive theory part details the major permeation processes of gases through porous polymers, being Fick's diffusion, Knudsen flow, and viscous flow. Both the measured stabilization time and the measured temperature dependence of the permeation rate independently indicate that the permeation can be described by a viscous flow model, where diffusion of the gas molecules in large pores (having a diameter of >0.05 µm) dominates.

show abstract

“…As C S of acetone is with 542 K very high (Hoffmann, 1962), µ roughly scales with T 3/2 . Therefore, the temperature dependence of the viscous flow can be expressed as:…”

Section: Viscous Flow (Large Pores)mentioning

confidence: 96%

An unheated permeation device for calibrating atmospheric VOC measurements

Brito

Zahn

2011

Atmos. Meas. Tech.

View full text Add to dashboard Cite

show abstract

“…with µ 0 (T 0 ) the gas viscosity at the reference temperature T 0 of typically 298.15 K and C S the Sutherland's constant. As C S of acetone is with 542 K very high (Hoffmann, 1962), µ roughly scales with T 3/2 . Therefore, the temperature dependence of the viscous flow can be expressed as:…”

Section: Viscous Flow (Large Pores)mentioning

confidence: 96%

An unheated permeation device for calibrating atmospheric VOC measurements

Brito¹,

Zahn²

2011

Preprint

View full text Add to dashboard Cite

The development of an unpowered permeation device for continuous calibration of in-situ instruments measuring atmospheric volatile organic compounds (VOCs) is described. Being lightweight and compact, and containing only negligible amounts of chemicals, the device is especially suited for field use such as onboard aircraft. Its speciality is to maintain the permeation process in thermal equilibrium, i.e. the instantaneous permeation rate can be ascribed via a simple temperature measurement. This equilibrium state is maintained by a combination of three features: (i) a thin PTFE membrane as permeation medium which guarantees short stabilization times, (ii) a water bath as heat buffer, and (iii) a vacuum-panel based insulation, in which features (ii) and (iii) minimize temperature drifts. The uncertainty of the permeation rate due to thermal non-equilibrium is kept below 1 %. An extensive theory part details the major permeation processes of gases through porous polymers, being Fick's diffusion, Knudsen flow, and viscous flow. Both the measured stabilization time and the measured temperature dependence of the permeation rate independently indicate that the permeation can be described by a viscous flow model, where diffusion of the gas molecules in large pores (having a diameter of >0.05 μm) dominates

show abstract

Geometrische Isomerenpaare mit bevorzugter cis‐Struktur, II. Die cis‐trans‐Isomerie beim 2‐Brom‐1‐jod‐äthylen

Viehe

Franchimont

1963

Chem. Ber.

View full text Add to dashboard Cite

Entgegen Literaturangaben kommt dem einzigen bisher bekannten 2-Brom-ljod-iithylen trans-Struktur zu. Dessen thermische Isomerisierung fiihrt nicht nur zum Gleichgewicht mit dem cis-Isomeren, das gaschromatographisch abtrennbar ist und dessen Eigenschaften beschrieben werden, sondern auch durch intermolekularen Halogenaustausch zu einem von allen Seiten erreichbaren Gleichgewicht der Isomerenpaare des 1.2-Dibrom-, 1.2-Dijod-und des 2-Brom-1 -jod-ilthylens. Gleichgewichtsmessungen fur das 2-Brom-I-jod-athylen bei 175 und 225' lassen bei Raumtemperatur knapp 50 % cis-Gehalt abschatzen. Somit ist beim 2-Brom-1-jod-athylen die G r e w erreicht fur die cis-Bevorzugung in der Reihe der zehn 1.2-Dihalogen-athylene, von denen nur das Dijod-athylen bei Normaltemperatur ausgeprlgt auf der tram-Seite liegt. Sein cidsomeres wurde erstmals rein dargestellt.

show abstract

Calculation to Relative Molar Response Factors of Thermal Conductivity Detectors in Gas Chromatography.

Cited by 25 publications

References 27 publications

An unheated permeation device for calibrating atmospheric VOC measurements

An unheated permeation device for calibrating atmospheric VOC measurements

An unheated permeation device for calibrating atmospheric VOC measurements

Geometrische Isomerenpaare mit bevorzugter cis‐Struktur, II. Die cis‐trans‐Isomerie beim 2‐Brom‐1‐jod‐äthylen

Contact Info

Product

Resources

About