Monodisperse silica nanoparticle suspension for developing latent blood fingermarks

Traditional fingermark developing methods are unsuitable for developing and extracting latent blood fingermarks on dark surfaces at crime scene because of their ineffectiveness or tedious operation procedures.In the present work,an effective and simple method was developed to serve this purpose using a suspension of monodisperse silica nanoparticles(MSNs).A suspension of 0.1 g/mL of MSNs was prepared by dispersing MSNs ultrasonically into an ethanol solution containing 1.0%Tween 80 and then uniformly sprayed onto the latent blood fingermarks on black plastic bags.Approximately 20 s later,ethanol was sprayed to clean the superfluous developing liquid.After the ethanol had evaporated,the latent fin-germarks became visible as a result of the photonic crystal effect produced by the MSNs that had adsorbed to the fingermark ridges.The developed fingermarks were then photo-graphed using a digital camera under a white or monospectral light source,revealing fine ridges and clear fingermark details.This novel,simple and effective method uses the pho-tonic crystal effect of MSNs to develop latent blood fingermarks without the need for sur-face functionalization and conjugation to dye or fluorescently label molecules.The method can detect latent blood fingermarks that have been retained on a black plastic bag surface for at least 30 d.Given the simplicity and effectiveness of the developed method,MSNs may be a useful alternative material for use in developing latent fingermarks.Further research on the topic is warranted.

The mechanical properties of plastic evidence bags used for collection and storage of drug chemicals relevant to clandestine laboratory investigations

The effectiveness of three types of plastic bags used by the New South Wales Police Force for the storage of clandestine drug evidence has been investigated through a comparison of mechanical properties.The tensile and tear properties of“as received”low-density polyethylene(LDPE)and poly(vinyl chloride)(PVC)bags do not show major differences such that one type would be favoured over the other.However,the mechanical properties of the bags once exposed to a range of chemicals routinely collected as drug evidence have been shown to be influenced as a result of different chemical interactions.Although an interaction of reagents/solvents with an additive within the LDPE bags is proposed to influence the mechanical properties of the bags,the change in properties has been shown to be less severe than that observed for the PVC bag,where softening and damage of the bags results due to absorption of reagents.

Isolation and identification of an isomeric sildenafil analogue as an adulterant in an instant coffee premix

The proliferation of adulterated health foods and beverages in the market demands a comprehensive analytical strategy to identify the adulterants,particularly those of isomeric phosphodiesterase 5(PDE5)inhibitors.An instant coffee premix(ICP)purchased from an online retailer was flagged for suspected adulteration through PDE5 inhibition assay.The ICP was then analysed using suspected-target and non-targeted screenings of a liquid chromatography-quadrupole time-of-flight mass spectrometry.Based on these findings,a PDE5 inhibitor initially assigned as compound X was isolated from the ICP by employing a liquid chromatography-diode array detection before its structural elucidation with liquid chromatography-ultraviolet(LC-UV)spectroscopy and nuclear magnetic resonance(NMR)spectroscopy.The suspected-target screening matched the protonated molecule([MþH]þ)precursor ion of compound X at m/z 499.2310 with two suspected analytes that are structural isomers of one another.The fragmentation patterns of compound X were comparable to those analogues in the dithiocarbodenafil group through the non-targeted screening.These findings,complemented by the LC-UV and NMR spectroscopy data,together with the chromatographic separation of related structural isomers,conclude the identity of compound X.To our best knowledge,this is the first study to report the presence of 3,5-dimethylpiperazinyl-dithiodesmethylcarbodenafil in an ICP sample.