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Skog KM, Xiong F, Kawashima H, Doyle E, Soto R, Gentner DR. Compact, Automated, Inexpensive, and Field-Deployable Vacuum-Outlet Gas Chromatograph for Trace-Concentration Gas-Phase Organic Compounds. Anal Chem 2019; 91:1318-1327. [DOI: 10.1021/acs.analchem.8b03095] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Kate M. Skog
- Department of Chemical & Environmental Engineering, School of Engineering and Applied Science, Yale University, New Haven, Connecticut 06511, United States
| | - Fulizi Xiong
- Department of Chemical & Environmental Engineering, School of Engineering and Applied Science, Yale University, New Haven, Connecticut 06511, United States
| | - Hitoshi Kawashima
- Department of Chemical & Environmental Engineering, School of Engineering and Applied Science, Yale University, New Haven, Connecticut 06511, United States
| | - Evan Doyle
- Department of Chemical & Environmental Engineering, School of Engineering and Applied Science, Yale University, New Haven, Connecticut 06511, United States
| | - Ricardo Soto
- Department of Chemical & Environmental Engineering, School of Engineering and Applied Science, Yale University, New Haven, Connecticut 06511, United States
| | - Drew R. Gentner
- Department of Chemical & Environmental Engineering, School of Engineering and Applied Science, Yale University, New Haven, Connecticut 06511, United States
- SEARCH (Solutions for Energy, Air, Climate and Health) Center, Yale University, New Haven, Connecticut 06511, United States
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2
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Sharif KM, Kulsing C, Marriott PJ. Pressure Tuning of First Dimension Columns in Comprehensive Two-Dimensional Gas Chromatography. Anal Chem 2016; 88:9087-94. [DOI: 10.1021/acs.analchem.6b02017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Khan M. Sharif
- Australian Centre for Research
on Separation Science, School of Chemistry, Monash University, Wellington
Rd., Clayton, Victoria 3168, Australia
| | - Chadin Kulsing
- Australian Centre for Research
on Separation Science, School of Chemistry, Monash University, Wellington
Rd., Clayton, Victoria 3168, Australia
| | - Philip J. Marriott
- Australian Centre for Research
on Separation Science, School of Chemistry, Monash University, Wellington
Rd., Clayton, Victoria 3168, Australia
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3
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Veschetti E, Notardonato I, Avino P, Russo MV. GC models for separation optimization in pressure-tuneable tandem capillary columns operated isothermally. Part 1: Theoretical aspects. J Sep Sci 2013; 36:2260-7. [DOI: 10.1002/jssc.201300233] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Revised: 04/03/2013] [Accepted: 04/23/2013] [Indexed: 11/05/2022]
Affiliation(s)
- Enrico Veschetti
- Istituto Superiore di Sanità; Dipartimento Ambiente e Connessa Prevenzione Primaria; Rome Italy
| | - Ivan Notardonato
- Università degli Studi del Molise; Dipartimento Agricoltura; Ambiente e Alimenti (DiAAA); Campobasso Italy
| | | | - Mario Vincenzo Russo
- Università degli Studi del Molise; Dipartimento Agricoltura; Ambiente e Alimenti (DiAAA); Campobasso Italy
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4
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Mommers J, Pluimakers G, Knooren J, Dutriez T, van der Wal S. Tunable secondary dimension selectivity in comprehensive two-dimensional gas chromatography. J Chromatogr A 2013; 1297:179-85. [DOI: 10.1016/j.chroma.2013.04.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 04/06/2013] [Accepted: 04/08/2013] [Indexed: 11/27/2022]
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5
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Mommers J, Knooren J, Dutriez T, Ritzen E, van der Wal S. Temperature-tunable selectivity in comprehensive two-dimensional gas chromatography. J Chromatogr A 2012. [DOI: 10.1016/j.chroma.2012.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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6
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Johns C, Shellie RA, Pohl CA, Haddad PR. Two-dimensional ion chromatography using tandem ion-exchange columns with gradient-pulse column switching. J Chromatogr A 2009; 1216:6931-7. [DOI: 10.1016/j.chroma.2009.08.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 08/03/2009] [Accepted: 08/10/2009] [Indexed: 10/20/2022]
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7
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Sanchez JM, Sacks RD. Performance characteristics of a new prototype for a portable GC using ambient air as carrier gas for on-site analysis. J Sep Sci 2007; 30:1052-60. [PMID: 17566340 DOI: 10.1002/jssc.200600367] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The performance characteristics of a portable GC instrument requiring no compressed gas supplies and using relatively lightweight transportable components for the analysis of volatile organic components in large-volume air samples are described. To avoid the need for compressed gas tanks, ambient air is used as the carrier gas, and a vacuum pump is used to pull the carrier gas and injected samples through the wall-coated capillary column and a photoionization detector (PID). At-column heating is used eliminating the need for a conventional oven. The fused silica column is wrapped with heater wire and sensor wire so that heating is provided directly at the column. A PID is used since it requires no external gas supplies and has high sensitivity for many compounds of interest in environmental air monitoring. In order to achieve detection limits in the ppb range, an online multibed preconcentrator containing beds of graphitized carbons and carbon molecular sieves is used. After sample collection, the flow direction through the preconcentrator is reversed, and the sample is thermally desorbed directly into the column. Decomposition of sensitive compounds during desorption is greater with air as the carrier gas than with hydrogen.
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Affiliation(s)
- Juan M Sanchez
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
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8
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Peng FM, Xie PH, Shi YG, Wang JD, Liu WQ, Li HY. Photoionization Detector for Portable Rapid GC. Chromatographia 2007. [DOI: 10.1365/s10337-006-0169-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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9
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Lambertus G, Elstro A, Sensenig K, Potkay J, Agah M, Scheuering S, Wise K, Dorman F, Sacks R. Design, Fabrication, and Evaluation of Microfabricated Columns for Gas Chromatography. Anal Chem 2004; 76:2629-37. [PMID: 15117208 DOI: 10.1021/ac030367x] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The design, fabrication, and performance of gas chromatography columns etched in silicon substrates are described. Deep reactive-ion etching formed the 3-m-long, 150-microm-wide, 240-microm-deep rectangular cross section channels. A glass cover plate was anodically bonded to the remaining surface of the substrate forming the gastight channel. For some of the columns, the silicon channels were oxidized before the channels were sealed with the glass plates. Fused-silica capillary connecting tubes were sealed into ports on the edge of the 3.2-cm x 3.2-cm substrate chips. Dynamic coating was used to deposit a film of nonpolar dimethyl polysiloxane or moderately polar trifluoropropylmethyl polysiloxane stationary phase. The columns were evaluated in a conventional benchtop GC instrument with split injection and flame ionization detection. Column efficiency was evaluated by the use of plots of height equivalent to a theoretical plate versus average carrier gas velocity using both hydrogen and air as carrier gases. The number of theoretical plates measured at the average carrier gas velocity giving the minimum plate height ranged from 4600 to 8200 plates for the dimethyl polysiloxane columns and from 3500 to 5500 plates for the trifluoropropylmethyl polysiloxane columns. Minimum plate height was significantly smaller with air as carrier gas. For the nonpolar phase, the nonoxidized surface gave approximately 1500 plates more than the oxidized surface for both carrier gases. For the polar phase, the oxidized surface gave approximately 200 plates more than the nonoxidized surface. Isothermal chromatograms of a 20-component multifunctional mixture and temperature-programmed chromatograms of a normal alkane mixture are presented.
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Affiliation(s)
- Gordon Lambertus
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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10
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Abstract
Fast gas chromatography-mass spectrometry (GC-MS) has the potential to be a powerful tool in routine analytical laboratories by increasing sample throughput and improving laboratory efficiency. However, this potential has rarely been met in practice because other laboratory operations and sample preparation typically limit sample throughput, not the GC-MS analysis. The intent of this article is to critically review current approaches to fast analysis using GC-MS and to discuss practical considerations in addressing their advantages and disadvantages to meet particular application needs. The practical ways to speed the analytical process in GC and MS individually and in combination are presented, and the trade-offs and compromises in terms of sensitivity and/or selectivity are discussed. Also, the five main current approaches to fast GC-MS are described, which involve the use of: (1) short, microbore capillary GC columns; (2) fast temperature programming; (3) low-pressure GC-MS; (4) supersonic molecular beam for MS at high GC carrier gas flow; and (5) pressure-tunable GC-GC. Aspects of the different fast GC-MS approaches can be combined in some cases, and different mass analyzers may be used depending on the analytical needs. Thus, the capabilities and costs of quadrupole, ion trap, time-of-flight, and magnetic sector instruments are discussed with emphasis placed on speed. Furthermore, applications of fast GC-MS that appear in the literature are compiled and reviewed. At this time, the future usefulness of fast GC-MS depends to some extent upon improvement of existing approaches and commercialization of interesting new techniques, but moreover, a greater emphasis is needed to streamline overall laboratory operations and sample preparation procedures if fast GC-MS is to become implemented in routine applications.
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Affiliation(s)
- Katerina Mastovská
- USDA, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
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11
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Whiting J, Sacks R. Programmable selectivity for GC with series-coupled columns using pulsed heating of the second column. Anal Chem 2003; 75:2215-23. [PMID: 12918958 DOI: 10.1021/ac020614h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series-coupled ensemble of a nonpolar dimethyl polysiloxane column and a polar trifluoropropylmethyl polysiloxane column with independent at-column heating is used to obtain pulsed heating of the second column. For mixture component bands that are separated by the first column but coelute from the column ensemble, a temperature pulse is initiated after the first of the two components has crossed the column junction point and is in the second column, while the other component is still in the first column. This accelerates the band for the first component. If the second column cools sufficiently prior to the second component band crossing the junction, the second band experiences less acceleration, and increased separation is observed for the corresponding peaks in the ensemble chromatogram. High-speed at-column heating is obtained by wrapping the fused-silica capillary column with resistance heater wire and sensor wire. Rapid heating for a temperature pulse is obtained with a short-duration linear heating ramp of 1000 degrees C/min. During a pulse, the second-column temperature increases by 20-100 degrees C in a few seconds. Using a cold gas environment, cooling to a quiescent temperature of 30 degrees C can be obtained in approximately 25 s. The effects of temperature pulse initiation time and amplitude on ensemble peak separation and resolution are described. A series of appropriately timed temperature pulses is used to separate three coeluting pairs of components in a 13-component mixture.
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Affiliation(s)
- Joshua Whiting
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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12
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Whiting J, Sacks R. Selectivity enhancement for high-speed GC analysis of volatile organic compounds with portable instruments designed for vacuum-outlet and atmospheric-pressure inlet operation using air as the carrier gas. Anal Chem 2002; 74:246-52. [PMID: 11795802 DOI: 10.1021/ac010879g] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A tandem ensemble of two 4.5-m-long x 0.25-mm-i.d. capillary columns with the first using a 0.50-microm film of nonpolar dimethyl polysiloxane and the second using a 0.25-microm film of polar trifluoropropylmethyl polysiloxane is operated with atmospheric pressure air as the carrier gas and an outlet pressure of 50.5 kPa established using a small vacuum pump. A thicker stationary-phase film is used in the first column to increase retention for very volatile compounds. This significantly increases the resolution of these compounds. The thicker film in the first (nonpolar) column decreases the polarity of the tandem column ensemble and, thus, changes its selectivity. A low-dead-volume valve, connected between the column junction point and a source of atmospheric pressure air, is used to obtain pulsed modulation of the carrier gas flow through the column ensemble. When the valve is open, the ensemble inlet pressure and the junction-point pressure are nearly the same, and carrier gas flow nearly stops in the first column, and flow in the second column increases. Enhanced resolution of a component pair that is separated by the first column but coelutes from the column ensemble can be obtained if the valve is opened for a few seconds after one of the components has crossed the junction and is in the second column, but the other component is still in the first column. A sequence of appropriately timed pulses is used to obtain enhanced resolution of several pairs of components that coelute from the column ensemble. These methods enabled the complete separation of an 18-component vapor mixture of common solvents in air in 3.5 min.
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Affiliation(s)
- Joshua Whiting
- Department of Chemistry, University of Michigan, Ann Arbor 48109, USA
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Whiting JJ, Lu CJ, Zellers ET, Sacks RD. A portable, high-speed, vacuum-outlet GC vapor analyzer employing air as carrier gas and surface acoustic wave detection. Anal Chem 2001; 73:4668-75. [PMID: 11605845 DOI: 10.1021/ac0103726] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vacuum-outlet GC with atmospheric-pressure air as the carrier gas is implemented at outlet pressures up to 0.8 atm using a low-dead-volume polymer-coated surface acoustic wave (SAW) detector. Increases in the system outlet pressure from 0.1 to 0.8 atm lead to proportional increases in detector sensitivity and significant increases in column efficiency. The latter effect arises from the fact that optimal carrier gas velocities are lower in air than in more conventional carrier gases such as helium or hydrogen due to the smaller binary diffusion coefficients of vapors in air. A 12-m-long, 0.25-mm-i.d. tandem column ensemble consisting of 4.5-m dimethyl polysiloxane and 7.5-m trifluoropropylmethyl polysiloxane operated at an outlet pressure of 0.5 atm provides up to 4 x 10(4) theoretical plates and a peak capacity of 65 (resolution, 1.5) for a 3-min isothermal analysis. At 30 degrees C, mixtures of vapors ranging in vapor pressure from 8.6 to 76 Torr are separated in this time frame. The SAW detector cell has an internal volume of < 2 microL, which allows the use of higher column outlet pressures with minimal dead time. The sensor response is linear with solute mass over at least 2-3 decades and provides detection limits of 20-50 ng for the vapors tested. The combination of atmospheric-pressure air as carrier gas, modest operating pressures, and SAW sensor detection is well-suited for field instrumentation since it eliminates the need for support gases, permits smaller, low-power pumps to be used, and provides sensitivity to a wide range of vapor analytes.
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Affiliation(s)
- J J Whiting
- Department of Chemistry, Center for Wireless Integrated Microsystems, University of Michigan, Ann Arbor 48109, USA
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14
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McGuigan M, Sacks R. Band-trajectory model for temperature-programmed series-coupled column ensembles with pressure-tunable selectivity. Anal Chem 2001; 73:3112-8. [PMID: 11467561 DOI: 10.1021/ac010136v] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A model and a spreadsheet algorithm is described for the prediction of solute-band migration trajectories in a series-coupled combination of two capillary GC columns with pressure-tunable and -programmable selectivity and operated under temperature-programmed conditions. The model takes into account the acceleration of carrier gas in the two columns as a result of decompression effects, the deceleration of carrier gas as a result of the increase in viscosity during temperature programming, the decrease in solute retention factors with increasing temperature during the temperature program, the differences in retention factors for the two columns, and programmed changes in the carrier-gas flow rates in the two columns during selectivity programming. In the model, the 20-meter-long column ensemble is divided into 1-cm-long intervals, and the carrier-gas velocity and column temperature are assummed to be constant in any interval. Migration times for all of the mixture solutes are computed for each column interval, and the solute-band positons in the column ensemble are plotted versus the running sum of these migration times to obtain band trajectory plots. The sum of these migration times for all 2,000 intervals gives the ensemble retention times for the solutes. Isothermal retention factors (k) for all of the mixture components at various column temperatures (Tc) are used as imput to the algorithm. Slope and intercept values of In(k) vs 1/Tc plots are used in the algorithm. General features of the model are tested using a mixture of C12-C24 normal alkanes. A mixture of polar and nonpolar compounds is used to test the utility of the model for the predicition of peak separations and retention times with pressure-tunable and -programmable selectivity. Good agreement is observed in all cases.
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Affiliation(s)
- M McGuigan
- Department of Chemistry, University of Michigan, Ann Arbor 48109, USA
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