Pressure and Modifier Programming in Packed-Column Supercritical Fluid Chromatography

Morrissey, Mark A.; Giorgetti, Aldo; Polášek, Miroslav; Periclès, N.; Widmer, Hans

doi:10.1093/chromsci/29.6.237

Cited by 15 publications

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“…This hypothesis is also supported by the results obtained when methanol and CO 2 are introduced separately into the ion source. Mass spectra obtained in these experiments show nearly the same cluster pattern as in experiments where the methanol is subjected to the adiabatic cooling, Figure 1a and 3 OH and a minor amount of ions at m/z 47, which corresponds to loss of H 2 O. The same pattern was observed in the CID spectrum of (CD 3 OD) 2 D ϩ m/z 74, where the main signal was found at m/z 38 and only trace amounts at m/z 54.…”

Section: Resultssupporting

confidence: 64%

“…A fragment ion formed from the protonated methanol is protonated formaldehyde, CH 2 OH ϩ at m/z 31, due to the elimination of H 2 . In addition, CH 3 ϩ at m/z 15 is also formed from protonated methanol after expulsion of water. The ions at m/z 29, HCO ϩ , appear only at a higher ion source repeller voltage (2 V or higher).…”

Section: Resultsmentioning

confidence: 99%

“…By analogy with methanol, one would expect two different structures for ions at m/z 97, (CH 3 OH) 3 The lack of m/z 79 and m/z 111 in the CID mass spectra of the protonated trimer and tetramer of methanol can be explained in terms of the level of internal energy of the clusters that decrease with increasing cluster size. As mentioned earlier, the internal energy of the clusters are important for further reactions, e.g., rearrangement or dissociation reactions.…”

Section: Resultsmentioning

confidence: 99%

“…Moderate and very polar compounds are poorly eluted due to low solute-solvent interactions [1]. Different approaches have been taken to address this limitation [2][3][4][5][6][7][8][9], and alternative fluids have been tested [10 -13]. Levy and Ritchey have described the effects of different modifiers on various functional classes of test solutes in 1986 [6].…”

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Ion-neutral reactions in the ion source of a mixture of CO₂/CH₃OH, CO₂/C₂H₅OH, and CO₂/2-C₃H₇OH by packed capillary supercritical fluid chromatography-mass spectrometry (SFC-MS)

Ekeberg

Jablonska-Jentoft

2007

J. Am. Soc. Mass Spectrom.

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Ion neutral reactions in the gas phase in mixtures of ROH/CO 2 , R ϭ CH 3 , C 2 H 5 , and 2-C 3 H 7 were studied by supercritical fluid chromatography-mass spectrometry (SFC-MS). Three main reaction series were found for this system; ionization followed by ␣-cleavage, formation of ␣ clusters, and formation of protonated dialkyl ethers from the corresponding alcohol. The ion chemistries were similar for the three alcohols, but that of 2-propanol was somewhat more complex. (J Am Soc Mass Spectrom 2007, 18, 2173-2179 [6]. When SFC is coupled to MS, the modifiers can form several reagent ions. The variety of reagents of different Brönsted acids gives the possibility to choose the correct reagent for a particular type of analysis [14,15]. The chemistry of ion-molecule interactions in the gas phase may provide an elegant substitute for the chromatographic preseparation step in conventional MS analysis. Pure CO 2 has been reported to act as a reagent gas for charge exchange (CE) with solute molecules [16 -18]. Using modified CO 2 , mixed CE/CI mechanisms can be reflected in the mass spectra [19]. This work presents results of the ionneutral reactions in the gas phase, which take place when mixtures of polar modifiers (methanol, ethanol, and 2-propanol) are introduced into the CO 2 mobile phase and expand through the direct fluid interface. The structure of the reagent ions were studied by collision induced dissociation (CID) and deuterium labeling. Previous reports of ion-neutral reactions in these alcohols [20 -24] provided an excellent basis for our study. ExperimentalInstrumentation SFC-MS data were collected by using an Isco 100DX syringe pump (Isco Inc., Lincoln, NE) attached to a double focusing mass spectrometer with EB geometry (DX303; JEOL, Tokyo, Japan). The SFC column was installed in a Carlo Erba high-resolution gas chromatograph (HRGC/MS; Instrument Teknikk Scandinavia AS, Oslo, Norway). The total ion chromatograms (TIC), reconstructed ion chromatograms (RIC), and mass spectra were recorded using Shrader interface and software (Shrader Analytical and Consulting Laboratories, Inc. Detroit, MI). Chromatography was performed using a 60 cm long, 450 m o.d., 320 m i.d., fused silica column packed with 5 m Intersil C 18 particles (Keystone Scientific Inc., Bellefonte, PA). The column outlet and the union connected to the column entrance were both equipped with a stainless steel frit with 2 m pore size (2400 Keystone Scientific). Valco zero dead volume unions (1/16 in. to 1/16 in.) were used. The injector (Valco C14W; Valco Instruments Co. Inc., Houston, TX) with 0.5 L injection loop was connected to the column by 7 cm long deactivated 50 m fused silica capillary tubing. Constant pressure in the chromatographic system was maintained by a 12 cm long, 15 m i.d. linear restricter. The temperature on the restricter tip was kept at 200°C, and the flow rate was 1.8 cm/s. The ion source temperature was 150°C and the column oven was held at 100°C. The electron energy used was 230 eV in CI mode. The pressure in the ion ...

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Section: Resultssupporting

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Ion-neutral reactions in the ion source of a mixture of CO₂/CH₃OH, CO₂/C₂H₅OH, and CO₂/2-C₃H₇OH by packed capillary supercritical fluid chromatography-mass spectrometry (SFC-MS)

Ekeberg

Jablonska-Jentoft

2007

J. Am. Soc. Mass Spectrom.

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“…Albeit numerous system improvements have been described by Widmer [261][262][263][264], they were not able to overcome a serious lack of robustness and reproducibility. This has somewhat limited its use for analytical purpose as well as in the pharmaceutical industry where it has remained in the shadow of LC considered today as a reference technique.…”

Section: Advantages and Limitations Of Sfcmentioning

confidence: 99%

Evolution and Current Trends in Liquid and Supercritical Fluid Chromatography

Fekete¹,

Perrenoud²,

Guillarme

2014

CCHG

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Abstract:The current trend in high performance liquid chromatography (HPLC) tends toward the achievement of higher separation efficiency and shorter analysis time. Indeed, better performance in LC has become increasingly important in recent years mainly driven by the challenges of either analyzing more complex samples or increasing the numbers of samples per time unit. In the recent development of particle technology, the use of fully porous sub-2 m particles and sub-3 m shell particles have received considerable attention. Beside packed columns, the new generation of silica-based monolithic columns also offers very high separation power. However, to take full advantage of these innovative phases, the chromatographic system has also to be drastically optimized in terms of upper pressure limit and system volume.This revolution in column technology now spreads and covers several modes of liquid chromatography such as reversedphase liquid chromatography (RPLC), hydrophilic interaction liquid chromatography (HILIC), or even supercritical fluid chromatography (SFC). The HILIC and SFC, which can be considered as alternative modes of chromatography, could also be useful to extend the applicability of chromatography towards the analysis of very hydrophilic and lipophilic compounds, respectively.The present review gives an insight about the theory behind the success of current column technology and presents a summary of latest applications, using various modes of one-dimensional chromatography (RPLC, HILIC, SFC). This paper also shows that theoretically expected column efficiency could sometimes be compromised in practical work especially in the case of narrow bore columns.

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Fluid phase equilibria in supercritical fluid chromatography with CO₂‐based mixed mobile phases: A review

Page

Sumpter

Lee

1992

J Microcolumn Separations

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Abstract. In supercritical fluid chromatography (SFC), cosolvents (modifiers) have been added to CO, in order to deactivate the analytical column and to improve the solvating power of CO, for extending the utility of SFC to polar and high molecular weight solutes. However, the use of modifiers has proven to be difficult, and irreproducibility in retention and selectivity is often observed.This comprehensive review focuses on the phase behavior of analytically useful C0,-based mixed mobile phases in SFC. All of the C0,-based mixed mobile phases which have been used in packed or open tubular column SFC are reviewed. All of the available fluid phase equilibria data for such binary fluids are discussed, and the P-T-x region which is applicable to SFC is compiled in both graphs and tables. Single phase regions (pressure and temperature) are listed by mol% modifier. However, only mixtures of CO, + benzene, + ethanol, + hexane, + methanol, or + toluene have enough P-T-x data points to enable extrapolation to any other conditions used in conventional SFC (0-20 mol% modifier, 40-400 atm, and 0-200°C). Problems associated with estimating the critical parameters of the pure components or the mixtures are reviewed. Phase transitions in the syringe pump, transfer lines, injector, column, and restrictor are delineated. Equilibration problems associated with the preparation of mixed mobile phases (premixed cylinders, liquid or gas phase saturation, and dual pumps with on-column mixing) and phase transitions during the operation of SFC instrumentation are discussed. Finally, future research needs are outlined.

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Pressure and Modifier Programming in Packed-Column Supercritical Fluid Chromatography

Cited by 15 publications

References 0 publications

Ion-neutral reactions in the ion source of a mixture of CO₂/CH₃OH, CO₂/C₂H₅OH, and CO₂/2-C₃H₇OH by packed capillary supercritical fluid chromatography-mass spectrometry (SFC-MS)

Ion-neutral reactions in the ion source of a mixture of CO₂/CH₃OH, CO₂/C₂H₅OH, and CO₂/2-C₃H₇OH by packed capillary supercritical fluid chromatography-mass spectrometry (SFC-MS)

Evolution and Current Trends in Liquid and Supercritical Fluid Chromatography

Fluid phase equilibria in supercritical fluid chromatography with CO₂‐based mixed mobile phases: A review

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Pressure and Modifier Programming in Packed-Column Supercritical Fluid Chromatography

Cited by 15 publications

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Ion-neutral reactions in the ion source of a mixture of CO2/CH3OH, CO2/C2H5OH, and CO2/2-C3H7OH by packed capillary supercritical fluid chromatography-mass spectrometry (SFC-MS)

Ion-neutral reactions in the ion source of a mixture of CO2/CH3OH, CO2/C2H5OH, and CO2/2-C3H7OH by packed capillary supercritical fluid chromatography-mass spectrometry (SFC-MS)

Evolution and Current Trends in Liquid and Supercritical Fluid Chromatography

Fluid phase equilibria in supercritical fluid chromatography with CO2‐based mixed mobile phases: A review

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Ion-neutral reactions in the ion source of a mixture of CO₂/CH₃OH, CO₂/C₂H₅OH, and CO₂/2-C₃H₇OH by packed capillary supercritical fluid chromatography-mass spectrometry (SFC-MS)

Ion-neutral reactions in the ion source of a mixture of CO₂/CH₃OH, CO₂/C₂H₅OH, and CO₂/2-C₃H₇OH by packed capillary supercritical fluid chromatography-mass spectrometry (SFC-MS)

Fluid phase equilibria in supercritical fluid chromatography with CO₂‐based mixed mobile phases: A review