Vol.:(0123456789) 1 3 Journal of the Iranian Chemical Society https://doi.org/10.1007/s13738-019-01823-y ORIGINAL PAPER 4, 4′‑Diamino‑4″‑methoxytriphenylamine as highly sensitive fluorimetric sensor for the determination of water in organic solvents Kiomars Zargoosh 1  · Mahshid Barmaki 1  · Amir Abdolmaleki 1  · Koorosh Firouz Tadavani 1 Received: 20 May 2019 / Accepted: 3 December 2019 © Iranian Chemical Society 2019 Abstract In this work, we report fast and low-cost fluorimetric system for the determination of trace amounts of water in both aprotic and protic organic solvents. The analytical signal of the proposed method is based on the quenching effects of water on the fluorescence emission spectrum of (4, 4′-diamino-4″-methoxytriphenylamine) molecule. It was found that physical inter- actions such as hydrogen bonding are responsible for the observed quenching effect. The limit of detection values for the determination of water in DMSO, acetonitrile, ethanol and methanol were 0.0727, 0.0636, 0.0761 and 0.0631 (W/W%), respectively. The limit of quantitation values in DMSO, acetonitrile, ethanol and methanol were 0.2734, 0.2546, 0.2540 and 0.2531 (W/W%), respectively. Simplicity, low cost and high speed of the proposed water sensing system make it a valuable candidate to be used in industrial applications such as quality control procedures. In addition, it can be used for the determi- nation of water in redox active solvents such as DMSO, where the standard Karl Fischer method gives problematic results. Keywords 4, 4′-Diamino-4″-methoxytriphenylamine · Ethanol · Methanol · DMSO · Water determination · Fluorescence Introduction Water as one of the impurities in the organic solvents can damage different laboratory instruments and interfere in the industrial processes such as pharmaceutical and petrochemi- cal production lines, food processing, paper production and fine chemical industry [1]. Therefore, determination of trace amounts of water in the organic solvents is an important research area. Classic and widely used technique for water determination in organic solvents is Karl Fischer method [2]. Although this method has several advantages includ- ing sensitivity and accuracy, some limitations such as use of toxic and expensive reagents, use of substantial amount of sample, slow reaction rate, requirement for skilled per- sonnel and possible interferences from redox active spices have restricted its application. To date, several methods such as chromatography [3], IR spectroscopy [4], potenti- ometry [5], Raman spectroscopy [6], solid-phase extraction [7], holographic method [8], absorbance-based film sen- sors [9], impedance-based electrochemical methods [10], conductometry [11] and amperometry [12] have been used for the determination of water in organic solvents. Most of these methods suffer from disadvantages like complexity in operation and cost of used materials. In addition, some of them cannot be used for the determination of water in redox active solvents such as dimethyl sulfoxide (DMSO). Nowadays, with the advancement of optical technology, fluorescence sensors have received a considerable attention for their applications in the determination of water contents of organic solvents. They are easy to fabricate and applicable in the remote and in situ monitoring. An ideal fluorescence- based sensor for water must exhibit high quantum yield and strong changes in its fluorescence intensity upon interacting chemically or physically with the water molecules. In recent years, many efforts have been made to achieve fluorescence sensors for the determination of water in different organic solvents [13]. In this paper, we report the fluorimetric method for the determination of low amounts of water in different organic solvents such as dimethyl sulfoxide (DMSO), acetonitrile (MeCN), ethanol and methanol using the quenching effect of water on the fluorescence intensity of the (4, 4′-diamino- 4″-methoxytriphenylamine) (DAP) molecules. The proposed system exhibits significant advantages including high sen- sitivity, rapid response, low-cost procedure and simplicity * Kiomars Zargoosh Kiomarszargoosh@cc.iut.ac.ir 1 Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran