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A novel 3D printed negative pressure small sampling system for bubble-free liquid core waveguide enhanced Raman
Jing Zhou1, Weicheng Chu2, Dong Lu3
1Institute of Quality Standard and Testing Technology for Agro-products, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-food Safety and Quality, Ministry of Agriculture, Beijing, 100081, China; Beijing Titan Instruments Company, Limited, Beijing, 100015, China.
This study introduces a novel negative pressure system combined with 3D printing to eliminate air bubbles in liquid core waveguide (LCW) enhanced Raman spectroscopy. This method improves analytical sensitivity and stability for quantitative analysis.
Area of Science:
- Analytical Chemistry
- Spectroscopy
- Materials Science
Background:
- Liquid core waveguides (LCWs) offer enhanced Raman spectroscopy with long optical paths and small sample volumes.
- Air bubbles in LCWs can cause scattering and refraction, hindering quantitative analysis.
- Existing methods for bubble removal are often inefficient or complex.
Purpose of the Study:
- To develop a novel negative pressure system integrated with 3D printing for bubble-free LCW enhanced Raman spectroscopy.
- To improve the sensitivity, stability, and reproducibility of Raman spectroscopy using LCWs.
- To demonstrate the system's effectiveness for analyzing real samples with minimal sample consumption.
Main Methods:
- A negative pressure system was designed using a diaphragm pump and magnetic valve controlled by a computer.
- A Teflon-AF LCW tube was integrated into a 3D-printed D-shaped support to create a sealed space.
- Adjustable negative pressure was applied to introduce samples and remove air bubbles through the tube wall.
- The system was tested for analyzing rhodamine B and ethanol in solutions using Raman spectroscopy.
Main Results:
- The system successfully eliminated air bubbles, enabling automated sample introduction and complete bubble removal.
- Analytical sensitivity was enhanced up to 82-fold for ethanol compared to traditional methods.
- Achieved limits of detection of 0.7 μg/mL for rhodamine B and 0.03% (v:v) for ethanol with 250 μL sample consumption.
- Demonstrated excellent linearity (r > 0.998) and high stability (intraday and 7-day reproducibility within 7%).
Conclusions:
- The proposed negative pressure LCW system offers a stable, sensitive, and rapid method for enhanced Raman spectroscopy.
- 3D printing facilitates an integrated and easily assembled detection system.
- The versatile system shows promise for various detectors and fast testing applications.
