流動注入分析訊號空時差異之進階研究

Abstract

一般小分子樣品在流動注入分析系統中，經由單通道偵測器所紀錄之隨流析時間得到的訊號圖形(訊號強度 v.s. 時間)常呈現拖尾的類高斯波形。根據本實驗室近年來之研究，若使用多通道偵測器觀察其空間的分布(訊號強度 v.s 樣品位置)，可以發現其空間分布的情形為一高斯對稱的波形。這兩種利用不同觀測方式(單通道 v.s 多通道)而得到的兩種波形之間的差異即為空時差異。 以奈米粒子當做流動注入分析系統的樣品時，其本身的單通道偵測器所記錄的訊號波形是非常特別的「雙峰」波形，因此本實驗想藉由多通道偵測器來觀測，是否空時差異的情形也會存在於奈米粒子的情況當中，並將奈米粒子與小分子樣品(tatrazine)兩者之空時差異情形進行比較。除此之外，本實驗也利用了相對標準偏差當作波形延散情形的指標，來對於波形的延散情形之空時差異進行探討。實驗的結果發現，兩種不同觀測方式得到的奈米粒子波形形狀的確存在著明顯差異的情形，但是此兩波形其相對標準偏差值卻是相似的。當時圖訊號的相對標準偏差為19.57%時，其波形還是以「雙峰」並存波形的形式呈現，然而以多通道偵測器所觀測到的相對應訊號，其相對標準偏差為22.25%時，卻已呈現相當高斯的波形。除此之外，本實驗還發現，時圖波形的相對延散（亦即相對標準偏差）情形與空時差異有很大的關係，當其相對延散的情形越大，則此條件下之兩者波形形狀的空時差異程度會越大，反之則越小，因此證明了相對延散的情況是影響波形形狀空時差異的一項重要的指標。並且藉由實驗的結果找到相對延散情形與各實驗參數(如：樣品擴散係數、管長等)的關係式。

The temporal signals of well diffusive solutes (typical small molecules) monitored using conventional single-channel detectors are usually Gaussian-like profiles with apparent tailing in flow injection analysis (FIA). According to the previous researches in our laboratory, the spatial signals monitored using the multi-channel detector were nearly Gaussian and symmetric under typical FIA conditions. The shape difference between the temporal and spatial profiles appeared due to the way how the measurements were conducted. The difference thus occurs is called spatial-temporal difference. It has been reported that the temporal signals of nanoparticles in FIA emerged usually as double-humped shapes, including so-called convection and diffusion peaks. In this study, we examined how the difference between the temporal and spatial profiles of tartrazine and Ag nanoparticles could come out using the laboratory-made multi-channel detector. The results showed a considerable difference between the temporal and spatial profiles for both solutes. However, their relative standard deviations, the parameter to describe the solute dispersion behaviors, turned out to be quite similar. The solute profile, acquired using the single-channel detection, was found to show somewhat double-hump character for Ag nanoparticles when the RSD was nearly 19.57%. However, the corresponding spatial signal of the same sample remained Gaussian with the RSD of 22.25%. In addition, the spatial-temporal difference became greater as the dispersion (RSD) of the temporal profile became larger. The dispersion was thus proved one of the major factors to affect the spatial-temporal difference. According to the results obtained using multi-channel detection, we also derived the relation between the signal RSD and other experimental factors including the molecular diffusion coefficient, and the tube length.