Performance of capillary restrictors in supercritical fluid chromatography

Smith, Richard D.; Fulton, John L.; Petersen, Robert C.; Kopriva, Andrew J.; Wright, Bob W.

doi:10.1021/ac00122a028

Cited by 102 publications

(53 citation statements)

References 15 publications

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“…Especially with triphenyl phosphate, spikes Were observed in the chromatogram at temperatures bellow 200 ~ By diluting the sample or increasing the presSUre, thc response could be partly restored and spiking Could be reduced. Spikes are thought to be caused by Cluster formation in the restrictor during decompression [25].…”

Section: H2mentioning

confidence: 99%

Packed-capillary supercritical fluid chromatography of pesticides using phosphorus-selective detection

et al. 1991

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SummaryPacked-capillary, supercritical fluid chromatography using carbon dioxide modified with methanol or 2-propanol as mobile phase, was coupled with a thermionic detector for Phosphorus-selective detection. Optimum conditions for thermionic detection were established for a number of hydrogen flow rates by adjusting the air flow rate and bead Position. Using the mentioned modifiers, a series of organOphosphorus pesticides of varying polarity could be separated within 8 min. An optimum sensitivity of 55-128 fg P/ s and linearity over four ordcrs of magnitude were obtained. The detector showed good selectivity for phosphorus Over carbon and nitrogen, viz., 9 9 104 g C/g P and 75 g N/ g P, respectively. This was demonstrated by determining pesticides such as phoxim, dimethoatc and azinphos-methyl In onion and tomato extracts.

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Section: H2mentioning

confidence: 99%

Packed-capillary supercritical fluid chromatography of pesticides using phosphorus-selective detection

et al. 1991

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“…This assumption will only be correct if the back pressure is higher than the exit pressure at sonic outlet conditions. It was shown by Smith et al that incomplete expansion of the fluid in the restrictor is likely to occur, especially when one uses restrictors with low length-to-diameter ratios (12). In this case, equation 2 is invalid because To test the validity of the assumptions leading to equation 2, a plot of the measured mass flow rate through the column is given in Figure 3 at different pressure drops over the variable restrictor (C).…”

Section: Theorymentioning

confidence: 99%

“…Deviations from linearity occurred only when the back pressure became lower than the vapor pressure of carbon dioxide at ambient temperature. In this case, a complex situation prevails in which liquid carbon dioxide evaporates in the restrictor at a position that depends on the pressure (12). After combining equations 1 and 2, the total flow rate through the column, F,o,, can be expressed by equation 3:…”

Section: Theorymentioning

confidence: 99%

Flow rate control in pressure‐programmed capillary supercritical fluid chromatography

Janssen

Rijks

Cramers

1990

J Microcolumn Separations

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Abstract. A versatile and simple system is described that allows variation of the column flow rate in open-tubular capillary supercritical fluid chromatography using both on-column and postcolumn detection. The system is based on column-effluent splitting in a low-dead-volume T piece at the column exit just before detection. The flow is split into two streams. One stream is fed to a flame ionization detector, and the second is used to control the overall mass flow through the column. Flow through linear restrictors is studied as a function of the pressure drop over the restrictor at ambient temperature. We derived a simple relationship from this study that quantifies the flow rate characteristics of the dual-restrictor system as a function of the column pressure and the restrictor back pressure.The variable-flow system was employed to control independently column pressure and mass flow rate in pressure-programmed analysis. Resolution in flow-controlled pressure-programmed elution was shown to be superior to that achieved in fixed-restrictor systems. Furthermore, the applicability of the system as a convenient means of measuring Van Deemter curves and diffusion coefficients is demonstrated.

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“…The relative merits of a variety of restrictor types have recently been discussed [5]. Incorporation of a mechanically pumped expansion region behind the CI repeller electrode has enabled much higher gas flow rates to be handled, thus allowing splitless capillary SFC and packed microbore LC columns to be used [6].…”

Section: Presented At the Eighth International Symposium On Capillarymentioning

confidence: 99%

Capillary and packed column SFC/MS

Berry¹,

Games²,

Mylchreest³

et al. 1988

J. High Resol. Chromatogr.

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Performance of capillary restrictors in supercritical fluid chromatography

Cited by 102 publications

References 15 publications

Packed-capillary supercritical fluid chromatography of pesticides using phosphorus-selective detection

Packed-capillary supercritical fluid chromatography of pesticides using phosphorus-selective detection

Flow rate control in pressure‐programmed capillary supercritical fluid chromatography

Capillary and packed column SFC/MS

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