Gold nanoparticle formation was found from tetrachloroaurate(III) in the presence of Good’s Buffers, such as 2-morpholinoethanesulfonic acid (MES) and 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (HEPES), which are used widely in laboratories for studies of analytical, inorganic, physical, and bio-chemistry as well as biology. The obtained gold nanoparticles were examined by Ultraviolet–Visible Spectroscopy (UV–vis), Dynamic Light Scattering (DLS) and Electrophoretic Light Scattering (ELS) in an aqueous system and by transmission electron microscopy (TEM) for particle morphologies. UV–vis spectra showed absorption maxima at ∼530 and ∼750 nm, depending on the buffer reagents and their concentration, pH, and ionic strength. The size and the surface zeta potential of the formed nanoparticles were 23 to 73 nm and −30 to −12 mV, respectively. The TEM pictures clearly indicated the formation of finely dispersed, chained, or aggregated gold nanoparticles, depending on the experimental conditions. The mechanism of gold nanoparticle formation was studied by the measurements of cyclic voltammetry (CV) and electron spin resonance (ESR). MES and HEPES showed a positive anodic peak at approximately +800 mV vs Ag/AgCl electrode, which indicated that these buffering agents have mild reducing ability. ESR results indicated the generation of nitrogen-centered cationic free radicals from these Good’s Buffers in the presence of Au(III), resulting in the formation of gold nanoparticles. A reaction mechanism is proposed.

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Because the major NOx(-) ions (x = 2, 3) produced in the plasma act as reagent ions in ion-molecule reactions of explosives, air is best suited as a carrier gas for the detection of explosives. It is proposed that the NOx(-) (x = 2, 3) and O3 contributed to the formation of [TNT-H](-) and [TNT-NO](-) ions, via the reactions NOx(-) + TNT → [TNT-H](-) + HNOx and [TNT](-) + O3 → [TNT-NO](-) + NO2 + O2.

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In analytical science, mass spectrometry (MS) is known as a “gold analytical tool” because of its unique character of providing the direct molecular structural information of the relevant analyte molecules. Therefore, MS technique has widely been used in all branches of chemistry along with in proteomics, metabolomics, genomics, lipidomics, environmental monitoring etc. Mass spectrometry-based methods are very much needed for fast and reliable detection and quantification of drugs of abuse and explosives in order to provide fingerprint information for criminal investigation as well as for public security and safety at public places, respectively. Most of the compounds exist as their neutral form in nature except proteins, peptides, nucleic acids that are in ionic forms intrinsically. In MS, ion source is the heart of the MS that is used for ionizing the electrically neutral molecules. Performance of MS in terms of sensitivity and selectivity depends mainly on the efficiency of the ionization source. Accordingly, much attention has been paid to develop efficient ion sources for a wide range of compounds. Unfortunately, none of the commercial ion sources can be used for ionization of different types of compounds. Moreover, in MS, analyte molecules must be released into the gaseous phase and then ionize by using a suitable ion source for detection/quantification. Under these circumstances, fabrication of new ambient ion source and ultrasonic cutter blade-based non-thermal and thermal desorption methods have been taken into account. In this paper, challenges and strategies of mass spectrometry analysis of the drugs of abuse and explosives through fabrication of ambient ionization sources and new desorption methods for non-volatile compounds have been described. We will focus the literature progress mostly in the last decade and present our views for the future study.

Nanocomposite ZnO-TiO 2 powders of varying ZnO/TiO 2 molar ratios have been prepared from their salt/compound by heating at 600°C and 900°C and characterized using scanning electron microscope and X-ray diffraction techniques. The nanosized powders can decolorize/degrade brilliant golden yellow (BGY), an azo dye extensively used in textile industries, in water under solar irradiation. The effects of various parameters such as photocatalyst loading, molar ratio of ZnO/TiO 2 , pH of the solution, initial dye concentration, and irradiation time on the photodecolorization have been investigated. ZnO-TiO 2 nanocomposite (6 g/L) in the molar ratio of 1:1 or 3:1, prepared at 900°C, can efficiently decolorize about 98% of 20 mg/L BGY at pH of about 7 by 2-h illumination in sunlight. The initial dye decolorization follows pseudo-first-order kinetics. Finally, trial experiments were done using real textile wastewater to find out the effectiveness of the photocatalysts to a more complex system.

Interactions of DNA with free base porphyrin, tetrakis(1-methylpyridium-4-yl)porphyrin (H 2 TMPyP 4+ ) and its metallo-derivative of ruthenium(II) have been investigated by UV-Vis, fluorescence and circular dichroism (CD) spectroscopy at 0.1 M NaCl, 7.5 pH and 25 °C. The results suggest that Ru(II)TMPyP 4+ interacts with DNA via outside binding in self-stacking manner as indicated by UV-Vis data, a small red shift (∆λ = 3 nm) and a minimal hypochromicity (10%) upon addition of DNA. CD spectra showed the presence of a new peak in the Soret region on addition of Ru(II)TMPyP 4+ to DNA solution. On the other hand, the interaction of free base porphyrin, H 2 TMPyP 4+with DNA revealed a significant hypochromicity (30%) and a large red shift (∆λ = 20 nm) in the UV-Vis results which conforms intercalation of free base porphyrin with DNA. In this case, the CD results showed only a negative peak developed in the Soret region during titration with DNA. Fluorescence spectroscopy revealed that initially aggregated porphyrin species were de-aggregated after addition of DNA. This phenomenon has been verified with the fluorescence experiments for the porphyrins in the presence of different concentrations of NaCl and ethanol. Ru(II)TMPyP 4+ showed enhanced DNA cleavage in the presence of EcoR1 restriction enzyme, where the enzyme did not cleave DNA. Metallo-porphyrins having the ability to cleave DNA could be used as chemotherapeutic agents for the treatment of African sleeping sickness (Trypanosomiasis).

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