奈米金表面電漿共振原理應用於中空光纖式氣相層析偵測器之研製

Abstract

本研究將中空光纖感測器串聯於氣相層析儀作為新型態有機揮發性氣體(Volatile Organic Compounds；VOCs)感測器。其原理乃利用奈米金屬粒子吸附有機氣體分子會造成局部性表面電漿共振(Localized Surface Plasmon Resonance；LSPR)光譜改變。本實驗所製備的奈米金粒子是利用檸檬酸鈉將四氯金酸(HAuCl4)還原成金原子，藉由自組裝薄膜反應機制將奈米金粒子修飾於中空光纖內層表面，其修飾劑為含有胺基(－NH2)的APTMS。將此感測器串聯於氣相層析儀，藉由綠光二極體(LED)提供一固定光源，穿過中空光纖管壁至另一端由綠光感測器所接收，當有機氣體流經層析管柱分離後，會被中空光纖表面的奈米金粒子所吸附而導致光強度有所變化，並利用雙低通濾波來提升綠光感測器之訊雜比及補償訊號飄移問題。此感測器成功地測試了十種混合有機氣體，結果顯示訊號反應迅速且具有良好的穩定性以及線性關係(R2≧0.99)，其偵測下限範圍可達60 ~ 185 ng，此偵測下限值比以往文獻中利用表面電漿共振原理來感測氣體還低。在未來的發展可將此奈米金中空光纖式表面電漿共振感測器應用於微小化氣相層析儀。

This research reports a novel optical hollow fiber device as a gas chromatographic detector for volatile organic compounds (VOCs). The detection is based on molecular adsorbed on the nanoparticle surface causing shifts in the localized surface plasmon resonance (LSPR) spectral peak. In this work, the sensing materials using gold nanoparticles were prepared via sodium citrate reduction of hydrogen tetrachlororaurate (HAuCl4). The gold nanoparticles were coated on the inner surface of optical hollow fiber by the self-assembled reaction between gold nanoparticles and surface amino groups (APTMS). The detection system was constructed on a bench-scale GC equipped with a separation column that was connected to the device, the light emitting diode (LED) as an light source and the light was passed through the wall of optical hollow fiber, when VOCs from GC column elutes through the optical hollow fiber, the gas molecules were adsorbed on gold nanoparticles caused changing the intensity of the light power transmitted. A green sensor was used to measure the intensity changes of light. A dual low-pass filter circuit was used to enhance signal/noise ratio for the green sensor and automatically compensated the baseline drift. The chromatogram of ten organic vapors plus water peak in background was successfully detected by our new detector. The result indicates that the detector peaks are sharp and responses are rapid, reversible, reproducible and linear (R2≧0.99) for all tested compounds. The limits of detection are ranging from 60 to 185 ng. All detection limit values were lower than that of previously reported gas sensing with LSPR system. This detector presented in this study shows good detection ability and has the potential for future integration with micro-GC system.