South African Journal of Chemistry - Volume 60, Issue 1, January 2007

A method for vanadium speciation is proposed. The method uses a low concentration eluent, 10 mmol L^-1 EDTA and 14 mmol L^-1 sodium carbonate, for the ion chromatographic separation of vanadium species at a flow rate of 1.2 mL min^-1. The quantitative detection limits were 0.14 mg L^-1 for V(IV) and 0.20 mg L^-1 for V(V) using ICP-OES detection. The method was successfully applied to the analysis of synthetic samples and mineral processing samples.

A quartz crystal microbalance (QCM) modified with a thin layer of fluorinated polymer was utilized to determine sarin. Determination was based on the frequency shifts due to the adsorption and desorption of the compound at the surface of a modified quartz crystal electrode. Fluorosiloxane was synthesized and deposited onto the surface of the sensor. The frequency shifts were linearly dependent on the concentration of sarin within the concentration range of 0.42 ppm to 3.85 ppm. Good selectivity and sensitivity for sarin were obtained with the sensor. The detection limit was 0.15 ppm.

Aldimines (Schiff's bases) undergo nucleophilic addition with diethyl/dimethyl/diphenylphosphite (Pudovik reaction) in the presence of a catalytic amount of tetramethylguanidine (TMG) at ambient temperature to afford the corresponding α-aminophosphonates in high yields. The Schiff's bases were prepared by reacting cinnamaldehyde with substituted amines in refluxing absolute alcohol. The structures of the title compounds were established by elemental analysis and IR, ¹H, ¹³C, ³¹PNMR and FAB mass spectral data. The antimicrobial activities of these compounds were evaluated and they exhibited significant antimicrobial activity.