Colorimetric paper-based devices with enhanced analytical performance for estimation of short post-mortem interval by total Fe detection in vitreous humor samples.

We report a paper-based analytical device for total Fe detection in vitreous humor to estimate the post-mortem interval (PMI) for forensic applications. This method improves a previously reported approach by replacing 1,10-phenanthroline (o-phen) with bathophenanthroline (bato-phen) as the chromogenic reagent, enhancing analytical performance. A linear response was obtained over the range from 0.0 to 10.0 mg L-1 for both reagents. The limits of detection (LOD) and quantification (LOQ) were 0.30 and 0.90 mg L-1 for o-phen, and 0.05 and 0.15 mg L-1 for bato-phen, respectively. The higher sensitivity of bato-phen is attributed to its greater molar absorptivity, resulting in improved colorimetric response. The method was applied to ten human vitreous humor samples, enabling PMI estimation on an hourly scale. The proposed device provides a rapid, low-cost, and portable alternative for preliminary PMI estimation directly at the crime scene.