研究目的
To fabricate resonance-tunable SERS-active capillaries for practical applications, specifically for the detection of thiram pesticide residues with high sensitivity, reproducibility, and stability.
研究成果
The fabricated resonance-tunable SERS-active capillaries demonstrate high sensitivity, reproducibility, and stability, with an enhancement factor of 6.09 × 10^6 and a detection limit of 10^-8 M for R6G. They enable long-term storage and signal tracking, and were successfully applied for in-situ detection of thiram residues on apple peels with a facile sampling process. These capillaries hold great potential for environmental analysis and other detection fields.
研究不足
The selectivity of the AuNR-coated capillaries is limited, as molecules that bind strongly to gold (e.g., via Au-S bonds) are detected more easily. This could lead to interference in complex samples. Additionally, the limit of detection for thiram (10^-7 M) is higher than some other methods like GC-MS, indicating room for improvement in sensitivity.
1：Experimental Design and Method Selection:
The study involved fabricating SERS-active capillaries by functionalizing gold nanorods (AuNRs) onto the inner walls of glass capillaries using electrostatic force. This method was chosen for its simplicity and effectiveness in achieving uniform coating and resonance tunability.
2：Sample Selection and Data Sources:
Glass capillaries with an inside diameter of
3：3 mm and length of 100 mm were used. Analytes included rhodamine 6G (R6G) and thiram solutions at various concentrations. List of Experimental Equipment and Materials:
Equipment included a Renishaw inVia Raman microscope system with He-Ne lasers (633 nm and 785 nm), JEM-1400 TEM microscope, Cary 5000 UV/Vis/NIR spectrophotometer, Sigma VP SEM, and COMSOL for numerical calculations. Materials included chemicals like CTAB, HAuCl4, APTES, and glass capillaries.
4：Experimental Procedures and Operational Workflow:
Capillaries were cleaned with piranha solution, functionalized with APTES to introduce amino groups, coated with AuNRs or AuNSs by aspiration, rinsed, and dried. Raman measurements were conducted with specific laser powers and acquisition times. For in-situ detection, thiram was sprayed on apple peels, extracted using capillaries with ethanol, and measured.
5：Data Analysis Methods:
Raman spectra were analyzed for intensity and reproducibility. Enhancement factor (EF) was calculated using standard equations. Statistical analysis included relative standard deviations (RSDs) for reproducibility assessment.
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