Assessing the reliability of wall-coated microfabricated gas chromatographic separation columns

Serrano, Gustavo; Reidy, Shaelah M.; Zellers, Edward T.

doi:10.1016/j.snb.2009.05.003

Cited by 61 publications

(56 citation statements)

References 37 publications

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“…26 (Note: the replacement of PDMS with a more polar stationary phase in one or both columns was considered during the development of the prototypes, but was ultimately rejected on the basis of the higher chromatographic efficiency and air stability of the PDMS phase). 20,30 Vapors eluting from the second microcolumn are detected by an integrated array of four chemiresistors (CR) (Figure 1e), each coated with a different thiolate-monolayer-protected Au nanoparticle (MPN) film. Responses in these devices arise from the transient change in film resistance accompanying sorption/ desorption of vapors into the MPN films.…”

Section: ■ Instrumentation and Methodologymentioning

confidence: 99%

Microfabricated Gas Chromatograph for On-Site Determination of Trichloroethylene in Indoor Air Arising from Vapor Intrusion. 1. Field Evaluation

Kim

Burris

Chang

et al. 2012

Environ. Sci. Technol.

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Results are presented of inaugural field tests of two identical prototype microfabricated gas chromatographs (μGC) adapted for the in situ determination of trichloroethylene (TCE) in indoor air in support of vapor intrusion (VI) investigations. Each μGC prototype has a pretrap and partially selective high-volume sampler of conventional design, a micromachined-Si focuser for injection, dual micromachined-Si columns for separation, and an integrated array of four microscale chemiresistors with functionalized gold nanoparticle interface films for multichannel detection. Scrubbed ambient air is used as the carrier gas. Field-generated calibration curves were linear for injected TCE masses of 26-414 ng (4.8-77 ppb·L; r(2) > 0.98) and the projected single-sensor detection limit was 0.052 ppb for an 8-L air sample collected and analyzed in 20 min. Consistent performance between the prototypes and good medium-term stability were shown. Above the mitigation action level (MAL) of 2.3 ppb for the field-test site, μGC TCE determinations fell within ±25% of those from the reference method for 21 of 26 measurements, in the presence of up to 37 documented background VOCs. Below the MAL, positive biases were consistently observed, which are attributable to background VOCs that were unresolvable chromatographically or by analysis of the sensor-array response patterns. Results demonstrate that this type of μGC instrument could serve the need for routine TCE determinations in VI-related assessment and mitigation efforts.

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Section: ■ Instrumentation and Methodologymentioning

confidence: 99%

Microfabricated Gas Chromatograph for On-Site Determination of Trichloroethylene in Indoor Air Arising from Vapor Intrusion. 1. Field Evaluation

Kim

Burris

Chang

et al. 2012

Environ. Sci. Technol.

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“…During testing, the coated μOFRR chip was connected by a short segment of deactivated fused silica capillary to two series-coupled, 3-m long microfabricated separation μcolumns with wall coatings of PDMS. The μcolumns consisted of square spiral channels deep reactive ion etched in Si (3.1 × 3.1 cm chips), an anodically bonded glass cover plate, and Pt resistive heaters and a temperature sensor patterned on the Si [12]. The μcolumns were held at 40 °C via on-chip heaters.…”

Section: Methodsmentioning

confidence: 99%

Multi-variable micro opto-fluidic ring resonator sensing with plasmonic nanoparticle films

Zhang

Wright

Scholten

et al. 2015

2015 Transducers - 2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS)

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Localized surface plasmon resonance (LSPR) in films of thiolate-and dithianate-monolayer-protected gold nanoparticles (MPN) having different monolayers and Au core sizes (4, 5, and 40 nm), and probed at three visible wavelengths near the LSPR maximum, has been exploited to discriminate among 6 vapors with a single sensing film. Arrays of just two MPN films (4-or 5-nm core diameters) were also remarkably selective (> 95% discrimination) even probing each film with just a single wavelength. Initial results obtained from the first MPN-coated microfabricated optofluidic ring resonator sensor (µOFRR) used as a µGC detector are also presented and appear promising.

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“…The μTM used for most testing was statically coated with PDMS from a solution that also contained 1% (w/w) dicumyl peroxide as the crosslinking agent using a published procedure [40,41]. The PDMS concentration was adjusted to produce an average (nominal) wall-coating thickness of 0.30 μm.…”

Section: µTm Assemblymentioning

confidence: 99%

Comprehensive two-dimensional gas chromatographic separations with a temperature programmed microfabricated thermal modulator

Collin

Nuñovero

Paul

et al. 2016

Journal of Chromatography A

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Comprehensive two-dimensional gas chromatography (GC×GC) with a temperature-programmed microfabricated thermal modulator (μTM) is demonstrated. The 0.78 cm(2), 2-stage μTM chip with integrated heaters and a PDMS coated microchannel was placed in thermal contact with a solid-state thermoelectric cooler and mounted on top of a bench scale GC. It was fluidically coupled through heated interconnects to an upstream first-dimension ((1)D) PDMS-coated capillary column and a downstream uncoated capillary or second-dimension ((2)D) PEG-coated capillary. A mixture of n-alkanes C6-C10 was separated isothermally and the full-width-at-half-maximum (fwhm) values of the modulated peaks were assessed as a function of the computer-controlled minimum and maximum stage temperatures of μTM, Tmin and Tmax, respectively. With Tmin and Tmax fixed at -25 and 100°C, respectively, modulated peaks of C6 and C7 had fwhm values<53 ms while the modulated peaks of C10 had a fwhm value of 1.3s, due to inefficient re-mobilization. With Tmin and Tmax fixed at 0 and 210°C, respectively, the fwhm value for the modulated C10 peaks decreased to 67 ms, but C6 and C7 exhibited massive breakthrough. By programming Tmin from -25 to 0°C and Tmax from 100 to 220°C, the C6 and C7 peaks had fwhm values≤50 ms, and the fwhm for C10 peaks remained<95 ms. Using the latter conditions for the GC×GC separation of a sample of unleaded gasoline yielded resolution similar to that reported with a commercial thermal modulator. Replacing the PDMS phase in the μTM with a trigonal-tricationic room temperature ionic liquid eliminated the bleed observed with the PDMS, but also reduced the capacity for several test compounds. Regardless, the demonstrated capability to independently temperature program this low resource μTM enhances its versatility and its promise for use in bench-scale GC×GC systems.

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Assessing the reliability of wall-coated microfabricated gas chromatographic separation columns

Cited by 61 publications

References 37 publications

Microfabricated Gas Chromatograph for On-Site Determination of Trichloroethylene in Indoor Air Arising from Vapor Intrusion. 1. Field Evaluation

Microfabricated Gas Chromatograph for On-Site Determination of Trichloroethylene in Indoor Air Arising from Vapor Intrusion. 1. Field Evaluation

Multi-variable micro opto-fluidic ring resonator sensing with plasmonic nanoparticle films

Comprehensive two-dimensional gas chromatographic separations with a temperature programmed microfabricated thermal modulator

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