Development of Natural Luminescent Powder for the Detection of Latent Fingerprint.

<b>Background and Objective:</b> Nowadays, Dyes is widely used to improve fingerprints identification test. Natural dyes are another interesting way that can be used instead of chemical dyes because of its non-toxicity and lower cost. In this research, the development of rust powder from <i>Plumeria</i> tree was applied for fingerprints identification due to its fluorescence property under UV. Rust and Small Particle Reagent (SPR), containing ZnCO₃were applied to detect hidden fingerprints on non-porous surfaces in both dried and wet condition. <b>Materials and Methods:</b> Yellowish Rust from <i>Plumeria</i> tree was extracted with ethanol, grinded, dried and then mixed with ZnCO₃. Powder slurry was sprayed over fingerprint mark on different surfaces and monitored in both dried and wet condition. Visualization of fingerprint under UV was observed. Scanning microscope (SEM), UV-visible spectroscopy (UV-VIS), Fourier-Transform Infrared Spectroscopy (FTIR) and Energy-Dispersive X-ray (EDX) were also used to characterize physical and chemical properties of rust powder. <b>Results:</b> Fingerprints identification by dust technique using <i>Plumeria</i> rust powder as ingredient, provide best quality enhancement of fingerprints under UV light due to its fluorescent property, whereas a conventional technique of Small Particle Reagent technique (SPR) doesn't show fluorescent under UV. Data from SEM and FTIR show slight adhesion between zinc carbonate particles and rust powder. <b>Conclusion:</b> Fluorescence properties of rust powder is still interesting. Further improvement in powder recipe will be further investigated.

A novel liquid colorimetric probe for highly selective and sensitive detection of lead (II).

A novel liquid colorimetric sensor based on deep eutectic solvent (DES) was developed for the preconcentration and detection of Pb2+ in fruit juice, milk and cereal samples. The colorimetric probe was simply fabricated by adding dithizone (DZ) into DES, prepared from choline chloride and phenol. Pb2+ was formed complex with DZ in the probe, providing hydrophobic complex of [Pb-DZ] which was simultaneously extracted into DES and the color was changed from light orange to carmine red. The enriched [Pb-DZ] in DES was detected using spectrophotometer at 520 nm and naked-eyes. In addition, a smartphone in combination with an Image J program was used as an alternative detection device. Under optimal conditions, the enrichment factor was 92 with LOD of 2.1 µg L-1 and the linear range was 0.007-0.075 mg L-1. The proposed liquid colorimetric sensor was successfully applied for Pb2+ detection in various food samples and the results were in good agreement with those obtained by FAAS. The advantages of this method are simple, rapid, environmental friendly and low cost.