Portable on-site colorimetric kit using stable gold nanorod powder for tracing hydrogen sulfide in typical environmental samples
Shuang Su, Zhiyang Zhang, Jiadong Chen, Yan Chen, Xin Cao, Shuoyang Yan, Ranran Yu, Jie Shao, Xiaokun Wang, Jaebum Choo, Lingxin Chen
Abstract
On-site detection of hydrogen sulfide (H 2 S), a toxic byproduct of microbial decomposition, is essential for environmental surveys, sewage tracing, and occupational safety. While existing gold nanorods (Au NRs)-based colorimetric methods offer portability and sensitivity, their practicality is hindered by the instability of enzymes and colloidal nanoparticles . Herein, we present an enzyme-free, portable H 2 S detection device using Au NRs powder, ensuring highly sensitive and reliable colorimetric detection while enhancing long-term applicability. The sensing strategy involves two steps: H 2 S microextraction and colorimetric assay . First, H 2 S is accumulated into a NaOH aqueous drop from a complex sample matrix via headspace single-drop microextraction (HS-SDME) using sulfamic acid . In the colorimetric assay, dissolved H 2 S reduces KIO 3 to I 2 in glycine-HCl buffer (pH 2.6), which etches Au NRs in the presence of Br - and CTA + , causing a blue shift in the plasmon band with a distinct color change. This method achieves a visual detection limit of 0.05 µM, approximately 10 times lower than the Methylene Blue method. The use of HS-SDME ensures excellent selectivity against co-existing ions (≥10-fold) and small organic molecules (100-fold). Validation with real samples yielded recoveries of 92.40 %-109.51 %, demonstrating reliability in environmental monitoring and river pollution tracing. To simplify detection, we developed a liquid-free test kit containing an H 2 S microextraction tube (sulfamic acid powder), a colorimetric assay tube (Au NRs powder and solid buffer), and a portable heating device. This enzyme-free sensor ensures long-term stability and practicality, advancing Au NRs-based sensors for environmental monitoring.