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Surface Nanodroplet-Based Extraction Combined with Offline Analytic Techniques for Chemical Detection and
Zhengxin Li1, Hongyan Wu1, Jae Bem You1,2
1Department of Chemical and Materials Engineering, University of Alberta, Alberta T6G 1H9, Canada.
Langmuir : the ACS Journal of Surfaces and Colloids
|September 6, 2022
Summary
Surface nanodroplet extraction offers a green method for analyte concentration. Collected nanodroplets enable sensitive detection of pollutants like triclosan and chlorpyrifos using standard analytical tools.
Area of Science:
- Analytical Chemistry
- Green Chemistry
- Separation Science
Background:
- Liquid-liquid extraction using surface nanodroplets is a sustainable technique for analyte concentration.
- The small volume of nanodroplets (<10 fL) limits in situ analytical techniques, often requiring specialized methods like surface-enhanced Raman spectroscopy.
- Demonstrating broader applicability of nanodroplet extraction is crucial for its adoption in routine analysis.
Purpose of the Study:
- To showcase the versatility of surface nanodroplet extraction beyond specialized in situ techniques.
- To develop a method for collecting and analyzing extracted analytes from surface nanodroplets using common offline analytical instruments.
- To validate the efficiency of this method for detecting environmental pollutants.
Main Methods:
- Octanol surface nanodroplets were formed and used for extraction within a 3 m Teflon capillary tube.
- Extracted nanodroplets were collected by injecting air, utilizing capillary forces to gather the droplets.
- ~10^12 nanodroplets were formed, allowing for the collection of ≥2 mL of octanol for subsequent analysis.
Main Results:
- Collected octanol volumes were sufficient for analysis by UV-vis, Gas Chromatography-Mass Spectrometry (GC-MS), and fluorescence microscopy.
- UV-vis spectroscopy coupled with nanodroplet extraction achieved reliable detection of triclosan and chlorpyrifos, showing a linear relationship between concentration and absorbance.
- Low limits of detection were achieved: 2 × 10^-9 M for triclosan and 3 × 10^-9 M for chlorpyrifos.
Conclusions:
- Surface nanodroplet extraction can be effectively coupled with common offline analytical techniques for sensitive detection.
- This method streamlines sample pretreatment, enabling sensitive chemical detection and quantification using standard analytical tools.
- The technique holds potential for environmental monitoring and other applications requiring efficient analyte preconcentration and analysis.
