Abstract
A new integrated microchip for liquid chromatography–mass spectrometry
(LC–MS) is presented. The chip is made from bonded silicon and glass
wafers with structures for a packed LC column channel, a micropillar
frit, a channel for optional optical detection, and a heated vaporizer
section etched in silicon and platinum heater elements on the glass
cover. LC eluent is vaporized and mixed with nebulizer gas in the
vaporizer section and the vapor is sprayed out from the chip. Nonpolar
and polar analytes can be efficiently ionized in the gas phase by
atmospheric pressure photoionization (APPI) as demonstrated with
polycyclic aromatic hydrocarbons (PAHs) and selective androgen receptor
modulators (SARMs). This is not achievable with present LC–MS chips,
since they are based on electrospray ionization, which is not able to
ionize nonpolar compounds efficiently. The preliminary quantitative
performance of the new chip was evaluated in terms of limit of detection
(down to 5 ng mL−1), linearity (r > 0.999), and repeatability of signal response (RSD = 2.6–4.0%) and retention time (RSD = 0.3–0.5%)
using APPI for ionization and PAHs as standard compounds. Determination
of fluorescent compounds is demonstrated by using laser-induced
fluorescence (LIF) for detection in the optical detection channel before
the vaporizer section.
Original language | English |
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Pages (from-to) | 163-169 |
Journal | Analytica Chimica Acta |
Volume | 662 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2010 |
MoE publication type | A1 Journal article-refereed |
Keywords
- Atmospheric pressure ionization
- Liquid chromatography
- Mass spectrometry
- Microchip
- Miniaturization