A dual-adsorbent preconcentrator for a portable indoor-VOC microsensor system

Chia-Jung Lu, E. T. Zellers

Research output: Contribution to journalArticle

103 Citations (Scopus)

Abstract

The development and testing of a miniature dual-adsorbent preconcentrator for a microsensor-based analytical system designed to determine complex volatile organic chemical (VOC) mixtures encountered in indoor working environments at low part-per-billion levels is described. Candidate adsorbents were screened for thermal-desorption bandwidth and breakthrough volume against 20 volatile organic vapors and subsets thereof as a function of several relevant variables. A glass capillary (1.1 mm i.d.) packed with 3.4 mg of Carbopack X and 1.2 mg of Carboxen 1000 provides sufficient capacity for a 1-L dry-air sample containing all 20 vapors at concentrations of 100 ppb as well as providing a composite half-height peak width of <3 s at a desorption temperature of 300 °C and a flow rate of 4 mL/min. Required adsorbent masses increase to 7.0 and 1.5 mg, respectively, for the same mixture at component concentrations of 1 ppm. Vapor breakthrough volumes for the Carbopack X are unaffected by humidity from 0 to 100%RH, but those for the Carboxen 1000 are significantly reduced, requiring an additional 0.9 mg of the latter to avoid premature breakthrough at the 100 ppb level. Good peak shapes, efficient chromatographic separation of preconcentrated sample mixture components, and detection limits in the low-parts-per-billion range using an integrated surface-acoustic-wave (SAW) sensor are achieved. Preconcentrator design and operating parameters are considered in terms of the vapor bed-residence times and breakthrough volumes in the context of the modified Wheeler equation.

Original languageEnglish
Pages (from-to)3449-3457
Number of pages9
JournalAnalytical Chemistry
Volume73
Issue number14
DOIs
Publication statusPublished - 2001 Jul 15

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Organic Chemicals
Microsensors
Humidity
Adsorbents
Glass
Limit of Detection
Hot Temperature
Vapors
Air
Temperature
Thermal desorption
Surface waves
Desorption
Atmospheric humidity
Flow rate
Acoustic waves
Bandwidth
Sensors
Composite materials
Testing

ASJC Scopus subject areas

  • Analytical Chemistry

Cite this

A dual-adsorbent preconcentrator for a portable indoor-VOC microsensor system. / Lu, Chia-Jung; Zellers, E. T.

In: Analytical Chemistry, Vol. 73, No. 14, 15.07.2001, p. 3449-3457.

Research output: Contribution to journalArticle

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