# Optical Detection of Water Adulteration in Ethanol Using PCPDTBT-Conjugated Polymer Nanoparticles

## TL;DR

Researchers developed a new optical method using polymer nanoparticles to detect water contamination in ethanol biofuels with high accuracy.

## Contribution

A novel optical sensing strategy using PCPDTBT-based conjugated polymer nanoparticles for rapid and sensitive water detection in ethanol.

## Key findings

- PCPDTBT nanoparticles showed dual-emission bands at 679 and 846 nm, with emission intensity ratios correlating strongly to water concentration.
- The method achieved a detection limit of 0.4% and quantification limit of 1.3% water in ethanol blends.
- Destabilization and aggregation of nanoparticles in ethanol enabled precise calibration for water adulteration detection.

## Abstract

The detection of water adulteration in ethanol biofuels
is a persistent
challenge due to ethanol’s high affinity for water and the
limitations of conventional analytical methods. In this study, we
present an innovative optical sensing strategy using conjugated polymer
nanoparticles (CPNs) composed of poly­[2,6-(4,4-bis­(2-ethylhexyl)-4H-cyclopenta-[2,1-b;3,4-b0]­dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) for rapid and sensitive
quantification of water content in ethanol blends. These nanoparticles
were synthesized via nanoprecipitation and exhibited dual-emission
bands centered at 679 and 846 nm, corresponding to nanoparticle fluorescence
and aggregation-related emissions, respectively. Upon exposure to
ethanol, destabilization of the CPN micelle structure and enhanced
aggregation were observed, leading to pronounced changes in the emission
profile. Notably, the emission intensity ratio (I
6
7
9/I
8
4
6) showed a strong linear correlation with
the water concentration, enabling precise calibration for water detection
and achieving limit of detection (LOD) and limit of quantification
(LOQ) values of 0.4 and 1.3% (v/v), respectively. These findings demonstrate
the strong potential of PCPDTBT CPNs as a sensitive and practical
platform for the future development of analytical tools to assess
biofuel quality and detect water adulteration in ethanol.