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Objective: Forensic and toxicological analyses of sedative-hypnotics require rapid and reliable screening techniques, particularly for seized materials and exhibits. In this study, a proof-of-concept workflow has been developed by integrating a paper-based analytical device (PAD), RGB colorimetric analysis, and gas chromatography–mass spectrometry (GC–MS) for the detection of alprazolam and phenobarbital.

Methods: Preliminary colour tests were considered for generating distinct coloured responses which produced characteristic blue and purple zones, respectively. Elution of the target analytes were achieved using solvent extraction method, following PAD-based screening, resulting in qualitative confirmation of analytes.

Results and Discussion: RGB analysis enabled objective differentiation and was used to estimate preliminary analytical parameters, including limit of detection (LOD = 24.5 and 29 µg/mL) and limit of quantification (LOQ = 81.6 and 96.8 µg/mL), with acceptable repeatability (%RSD < 2). Subsequent GC–MS analysis produced well-resolved peaks at retention times of 14.15 and 7.17 min, with characteristic fragmentation patterns and high similarity indices against the NIST Mass Spectral Library, confirming analyte identity. The non-volatile and thermo-labile nature of reagent-derived components, along with thermal dissociation processes occurring in the injection port may have resulted in absence of interfering peaks.

Conclusion: This proof-of-concept study demonstrates a simple yet effective integration of presumptive and confirmatory techniques, providing a rapid, portable, and cost-effective screening approach. The proposed workflow establishes a practical analytical bridge suitable for forensic and toxicological applications for exhibit level analysis, and offers the foundation for further method development and validation.