Abstract
ABSTRACT
Considering the growing global abuse of methamphetamine (MA) and its related public health and social consequences, developing rapid and sensitive point‐of‐care testing (POCT) methods for forensic applications has attracted increasing attention. This study developed an iron‐ and zinc‐doped carbon dots (Fe,Zn@PEI‐CDs)–based smartphone‐integrated fluorescent sensor using a simple one‐pot hydrothermal synthetic procedure. The fluorescence intensity of the Fe,Zn@PEI‐CDs at 360/452 nm (excitation wavelength/emission wavelength) was significantly increased upon exposure to MA through an aggregation‐induced emission (AIE) mechanism. The sensor displayed excellent linearity (
R
2
= 0.991) over the 60‐ to 600‐μg/mL range. Irradiation with 365‐nm ultraviolet light resulted in a distinct fluorescence color transition from light blue to dark blue. The values of the red (R), green (G), and blue (B) channels for the captured images were determined by a smartphone‐installed color picker application, and a grayscale analysis model was then constructed for visually detecting MA, yielding a limit of detection of 14.61 μg/mL. The proposed method was validated using urine samples, displaying recovery values ranging from 98.37% to 103.34% with relative standard deviations of less than 3.0%. These results provide a reliable method for detecting MA and offer a new solution for the rapid analysis of illicit drugs.