Novel gas chromatographic detector utilizing the localized surface plasmon resonance of a gold nanoparticle monolayer inside a glass capillary

This paper presents the design, assembly, and evaluation of a novel gas chromatographic detector intended to measure the absorbance of the localized surface plasmon resonance (LSPR) of a gold nanoparticle monolayer in response to eluted samples from a capillary column. Gold nanoparticles were chemically immobilized on the inner wall of a glass capillary (i.d. 0.8 mm, length = 5-15 cm). The eluted samples flowed through the glass capillary and were adsorbed onto a gold nanoparticle surface, which resulted in changes in the LSPR absorbance. The LSPR probing light source used a green light-emitting diode (LED; λ_center = 520 nm), and the light traveled through the glass wall of the capillary with multiple total reflections. The changes in the light intensity were measured by a photodiode at the rear of the glass capillary. The sensitivity of this detector can be improved by using a longer spiral glass capillary. The detector is more sensitive when operated at a lower temperature and at a slower carrier velocity. The calibration lines of 8 preliminary test compounds were all linear (R² > 0.99). The detection limits (3π) ranged from 22 ng (n-butanol) to 174 ng (2-pentanone) depending on the volatility of the chemicals and the affinity to the citrate lignads attached to the gold nanoparticle surface. This detector consumed a very low amount of energy and could be operated with an air carrier gas, which makes this detector a promising option for portable GC or μGC.