Detection of Trace Amounts of Water in Organic Solvent by 8-Hydroxypyrene-1,3,6-Trisulfonic Acid Trisodium Salt

Abstract

A colorimetric and fluorescent sensor was developed based on 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS) for the detection of trace amounts of water in polar organic solvents. Fluorescence and UV-visible absorption spectra of HPTS were measured in a variety of organic solvents (DMF, DMSO, ethanol, methanol). Fluorescence maxima comparable with maximum/minimum ratios were determined by using UV-visible absorption spectroscopy. The HPTS sensor exhibits high sensitivity for water with a detection limit as low as 0.0001 to 0.0005 wt-%. In addition, naked-eye inspection of solutions of HPTS sensor in organic solvents before and after addition of water showed dramatic changes in colour from blue to green. These findings can be applied in the use of HPTS as a molecular probe for trace amounts of water in organic solvents.

Reversible Colorimetric Sensor for Moisture Detection in Organic Solvents and Application in Inkless Writing

“…Therefore, a low-cost, simple, rapid, and highly sensitive portable device is required to detect trace levels of water in organic solvents and fine chemicals. Many sensitive fluorescent-based moisture sensors are available in the literature. − However, colorimetric detection is a simple and convenient method compared to the other traditional and fluorescent methods. Colorimetric moisture sensors express a color change in the presence of moisture which could be detected by the naked eye without any sophisticated analytical instrumentation facility.…”

A series of caged fluorophores for calibrating light intensity

“…In the first step, ester 1 was produced in 92% yield from acylating the HPTS phenol with acetic anhydride. 35 In the next step, its sulfonic acid groups were converted to chlorosulfonyl groups by reacting with oxalyl chloride to form compound 2 , which was used for the next step without any further purification.…”

“…As a uorophore scaffold, we chose 8-hydroxypyren-1,3,6trisulfonic acid (HPTS, pyranine). This bright uorophore is commercially available and highly water soluble, and it has found a wide range of applications as a tracer 35,36 or as a pH indicator with a pK a equal to 7.3. 37 Aer activation of the sulfonic groups, HPTS can be derivatized using nucleophiles to yield sulfonic esters and sulfonamides.…”

Proton Transfer Reaction Dynamics of Pyranine in DMSO/Water Mixtures

“…In neat DMSO, HPTS displays only a single emission maximum, centered at 430 nm, which arises from the excited‐state protonated form (ROH*) of HPTS. The presence of a single emission band at 430 nm has been previously reported for HPTS in various non‐aqueous solvents like methanol, DMSO, ethanol, DMF, etc., in which proton transfer is reported to be absent owing to the lack of proton acceptor species. Further, the emission spectrum of HPTS in neat DMSO was found to be slightly structured in nature, which has been attributed to the vibrational transitions of the pyrene derivatives in less polar solvents .…”

“…In al arge number of proton transfer studies performed on HPTS, the proton acceptor is water.The emission spectra of HPTS in bulk water displays two different emission bands, as trongp eak for the deprotonated form (RO À *) at 510 nm, arising owing to deprotonation occurring in the excited state, and aw eak peak at 430 nm correspondingt ot he protonated form (ROH*),a rising owing to excitationo fb ulk molecules from the ground state to excited state or it is ar esult of ag eminater ecombination of the dissociated proton and RO À *t aking place in the excited state. [45] In non-aqueous medial ike methanol, DMF, ethanol, etc.,t he emission band only at 430 nm is observed, [50,51] indicating either dramatic slowdowno ft he proton transfer reaction or the complete lack of it. Among the binary aqueous mixtures that are the subjecto fi nvestigation in the presenta rticle, althoughaconsiderable number of protont ransfer studies have been performed in various binarym ixtures, [52][53][54][55][56] there are only al imited number of reports of protont ransfer reactions in DMSO/water mixtures.…”