Flame-based thermionic detection coupled on-line with microcolumn liquid chromatography

Kientz, Ch.E.; Verweij, A.; Jong, Gerhardus J. de; Brinkman, U.A.Th.

doi:10.1016/0021-9673(92)85330-v

Cited by 6 publications

(4 citation statements)

References 10 publications

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“…The use of water as an LC carrier is potentially attractive since water has no significant FID response, and its use generates no organic solvent waste. While the most common modes of detection used with water as an LC carrier are spectrographic (UV or fluorescence), there have been several reports of thermionic and flame emission detectors having been adapted for use with liquid water. − A few early attempts have also been made to adapt an FID for use with water. Rudenko and Nonaka 7 used steam as a mobile phase for packed-column gas chromatography with FID and a flow rate of steam of 5−20 mL/min (corresponding to ∼4−16 μL/min liquid water).…”

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confidence: 99%

Subcritical Water Chromatography with Flame Ionization Detection

1997

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A chromatographic method has been developed that allows subcritical (hot/liquid) water to be used as a mobile phase for packed-column reverse-phase LC with solute detection by flame ionization detection. Detection limits (S/N > 3:1 for butanol) of 1 ng were achieved with water flows of 20 and 50 µL/min and 5 ng with flows ranging from 100 to 200 µL/min. Quantitative determinations of ethanol in alcoholic beverages are in excellent agreement with label values and replicate injections have RSDs of ∼2%. Increasing the column temperature lowers the dielectric constant (polarity) of water, decreases the elution time, and improves the peak shape for compounds ranging from alcohols to hydroxy-substituted benzenes to amino acids. Temperature programming up to 175 °C can be used to improve separations and decrease analysis times.

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confidence: 99%

Subcritical Water Chromatography with Flame Ionization Detection

1997

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“…In our earlier work 16-19 on the coupling of micro-LC with GC detectors, it was found that by combining heating and sufficient cooling, only a small zone (<1 mm) at the end of the liquid introduction capillary is heated. The thermal heat at that zone, which was originally generated by the detector flame, results in a pulsed evaporation and subsequently presumed plug-type liquid introduction as discussed earlier . In the recent interface, the thermal heat is delivered by the inductive heating of a small metal ring (see Figure ).…”

Section: Resultsmentioning

confidence: 95%

“…In recent years, we have extensively studied the on-line coupling of micro-LC and flame-based GC detectors and the use of thermospray LC/MS for the trace-level determination of nonvolatile organophosphoric and alkylphosphonic acids. − Recently, we accomplished the coupling of CE with flame photometric detection (FPD) . These studies were carried out for the identification of chemical warfare agent degradation products needed in view of the recent Convention on Chemical Weapons.…”

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confidence: 99%

Eluent Jet Interface for Combining Capillary Liquid Flows with Electron Impact Mass Spectrometry

Kientz¹,

Hulst²,

Jong³

et al. 1996

Anal. Chem.

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A new interface based on an eluent jet in combination with a conventional gas chromatography momentum separator for use with electron impact mass spectrometry is described. The formation of the eluent jet is based on radio frequency inductive heating. The aerosol formation in the interface is discussed in relation to commercial particle beam (PB) interfaces. The interface is tested in combination with electron impact mass spectrometry using flow injection analysis at flow rates in the range of 5-15 µL/ min commonly encountered in microcolumn liquid chromatography. Electron impact spectra at 1-10-ng levels are found to be comparable with reference spectra. In the single-ion mode, 50 pg of caffeine is detectable with a signal-to-noise ratio of 3:1. Contrary to many other PB systems, linear calibration plots are obtained in the tested range of 3-200 ng of caffeine.In 1984, Willoughby and Browner 1 introduced a new mass spectrometer interface that allowed both electron impact (EI) and chemical ionization (CI) in combination with liquid chromatography (LC). Based on this principle, many commercially available particle beam (PB) interfaces are successfully being used for the analysis of molecules that are not compatible with gas chromatography/mass spectrometry (GC/MS) methods. The systems are based on eluent nebulization, either pneumatical or by thermospray, into a desolvation chamber which is connected to a momentum separator where the high molecular weight analytes are preferentially transferred to the MS ion source, while the low molecular weight solvent molecules are efficiently pumped away. The use of PB interfaces has shown great promise, since the EI spectra obtained contain the fragmentation patterns necessary for unambiguous identification. However, quantitative analysis has been limited by fluctuations in absolute response observed in intraand interday runs and nonlinearity at lower concentrations. [2][3][4][5][6][7][8][9]

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“…Total eluent introduction schemes are rarely used with general response detectors such as an FID, because the analyte signal is obscured by the organic modifier in the LC eluent. As a result, element-specific detectors such as the electron capture detector, − the thermionic detector, − and the flame photometric detector have seen the most use for LC. Previously, in order to utilize the FID as an LC detector, the organic modifier had to be removed prior to analyte detection.…”

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confidence: 99%

Simultaneous Flame Ionization and Absorbance Detection of Volatile and Nonvolatile Compounds by Reversed-Phase Liquid Chromatography with a Water Mobile Phase

1997

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A flame ionization detector (FID) is used to detect volatile organic compounds that have been separated by water-only reversed-phase liquid chromatography (WRP-LC). The mobile phase is 100% water at room temperature, without use of organic solvent modifiers. An interface between the LC and detector is presented, whereby a helium stream samples the vapor of volatile components from individual drops of the LC eluent, and the vapor-enriched gas stream is sent to the FID. The design of the drop headspace cell is simple because the water-only nature of the LC separation obviates the need to do any organic solvent removal prior to gas phase detection. Despite the absence of organic modifier, hydrophobic compounds can be separated in a reasonable time due to the low phase volume ratio of the WRP-LC columns. The drop headspace interface easily handles LC flows of 1 mL/min, and, in fact, compound detection limits are improved at faster liquid flow rates. The transfer efficiency of the headspace interface was estimated at 10% for toluene in water at 1 mL/min but varies depending on the volatility of each analyte. The detection system is linear over more than 5 orders of 1-butanol concentration in water and is able to detect sub-ppb amounts of o-xylene and other aromatic compounds in water. In order to analyze volatile and nonvolatile analytes simultaneously, the FID is coupled in series to a WRP-LC system with UV absorbance detection. WRP-LC improves UV absorbance detection limits because the absence of organic modifier allows the detector to be operated in the short-wavelength UV region, where analytes generally have significantly larger molar absorptivities. The selectivity the headspace interface provides for flame ionization detection of volatiles is demonstrated with a separation of 1-butanol, 1,1,2-trichloroethane (TCE), and chlorobenzene in a mixture of benzoic acid in water. Despite coelution of butanol and TCE with the benzoate anion, the nonvolatile benzoate anion does not appear in the FID signal, allowing the analytes of interest to be readily detected. The complementary selectivity of UV-visible absorbance detection and this implementation of flame ionization detection allows for the analysis of volatile and nonvolatile components of complex samples using WRP-LC without the requirement that all the components of interest be fully resolved, thus simplifying the sample preparation and chromatographic requirements. This instrument should be applicable to routine automated water monitoring, in which repetitive injection of water samples onto a gas chromatograph is not recommended.

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Flame-based thermionic detection coupled on-line with microcolumn liquid chromatography

Cited by 6 publications

References 10 publications

Subcritical Water Chromatography with Flame Ionization Detection

Subcritical Water Chromatography with Flame Ionization Detection

Eluent Jet Interface for Combining Capillary Liquid Flows with Electron Impact Mass Spectrometry

Simultaneous Flame Ionization and Absorbance Detection of Volatile and Nonvolatile Compounds by Reversed-Phase Liquid Chromatography with a Water Mobile Phase

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