以多通道偵測器觀察流動注入分析訊號之空時差異

Abstract

流動注入分析法是一種使用相當廣泛的自動化分析技術，其記錄訊號的波形常呈現不對稱，並且有拖尾(tailing)的現象。根據傳統理論的解釋，產生波形拖尾的主要原因是由於流體以層流形式流動，使得樣品在管路內產生分散現象，以及管路本身的瑕疵使得流體產生變化。最近有文獻中提出時間效應的假說，由於樣品在管內的空間分佈狀態隨時間一直在改變，而傳統單通道偵測器收集到的訊號其實是樣品在管內不斷變化累積的結果，使得測量結果與樣品在管路內的空間分佈並不相同，因而產生訊號拖尾之結果。 本研究以多通道偵測器觀察流動注入分析系統中，樣品在管路內的空間分佈狀態(空圖)，以及記錄隨流析時間得到的訊號圖形(時圖)，對實驗所得波形各指標參數，包含不對稱因子、分散係數等進行比較，以及進行「空時疊圖」的波形比較，發現空圖與時圖有很明顯的「空時差異」，實驗結果符合空時扭變高斯方程式的理論基礎，證明傳統偵測器所得的波形呈現拖尾的原因，有很大比例是由「時間效應」造成的。並證明經驗分散係數的計算方法可得到樣品在管內的分散係數平均值。

Flow injection analysis (FIA) is widely used as an automatic analysis technology. The FIA signals often appear in asymmetric tailing peaks. According to the traditional theory, the tailing phenomenon occurs because the fluid moves in the form of laminar flow that results in dispersion in the FIA manifolds. Furthermore, the defects of the hardware itself also contributes to the fluid change, thus to the skewness of the peak shape. Recently a hypothesis of temporal effect is proposed to explain the tailing phenomenon. Because the spatial distribution of the sample in the FIA manifolds changes with time, the recorded signal from a traditional single-channel detector is actually the accumulation result of the constant signal variation of the sample in the manifold. Accordingly, the recorded signal as a function of time is different from the true spatial distribution of the sample in the manifold. This phenomenon results in tailing peak, even though the spatial distribution of the sample appears considerably symmetric. This research scrutinizes the spatial distribution of the sample in the FIA manifolds and the peak shape recorded as a function of time simultaneously using a multi-channel detector. Obvious difference is observed by comparing peak shapes between spatial and temporal profiles. This study confirms that the temporal effect is the major factor for the skewed FIA peaks. In addition, the theoretical foundation of the temporally convoluted Gaussian equation proposed in the literature is verified. Furthermore, the method for calculating the dispersion coefficient using the temporal signal is validated by the experimental spatial signal.