π-Selective stationary phases: (I) Influence of the spacer chain length of phenyl type phases on the aromatic and methylene selectivity of aromatic compounds in reversed phase high performance liquid chromatography

Phenyl type stationary phases of increasing spacer chain length (phenyl, methyl phenyl, ethyl phenyl, propyl phenyl and butyl phenyl, with 0–4 carbon atoms in the spacer chain, respectively) were synthesised and packed in house to determine the impact that the spacer chain length has on the retention process. Two trends in the aromatic selectivity, q_aromatic, were observed, depending on whether the number of carbon atoms in the spacer chain is even or odd. Linear log k′ vs ϕ plots were obtained for each stationary phase and the S coefficient was determined from the gradient of these plots. For the phenyl type phases, the S vs n_c plots of the retention factors of linear polycyclic aromatic hydrocarbons vs the number of rings exhibit a distinct discontinuity that between 3 and 4 rings, which increases with increasing spacer chain length for even phases but decreases for odd phases. Accordingly, we suggest that the retention factors depend differently on the number of carbon atoms in the spacer chain depending on whether this number is even or odd and that this effect is caused by different orientations of the aromatic ring relative to the silica surface.

Inhibition of corrosion on AA2024-T3 by rare earths & mercaptoacetate

The use of the aluminium alloy AA2024-T3 has long been associated with a strong vulnerability to localised corrosion. Dealloying and pitting corrosion can occur on and around intermetallic particles when exposed to aggressive environments such as sodium chloride electrolytes. Specific combinations of rare earths and organic compounds have demonstrated strong synergistic inhibition on the AA2024-T3 alloy. This work has focused on rare earths and organic compounds containing thiol functional groups. It is believed that the sulphur in the thiol group can form protective films over the surface of copper-rich intermetallic particles due to the affinity between copper and sulphur. Previous studies with the multiwell tests have identified that solutions containing sodium mercaptoacetate provided strong inhibition at pH 3 and 6. This work presents the initial findings from the polarisation tests and constant immersion corrosion experiments in the presence of sodium mercaptoacetate.

Chemiluminescence detection of piperazine designer drugs and related compounds using tris(2,2?-bipyridine)ruthenium(III)

 An exploration of the chemiluminescence from reactions of a large number of benzyl and phenylpiperazine analytes with tris(2,2’-bipyridyl)ruthenium(III) was carried out providing information towards the emission intensity of this chemiluminescent reagent and the structure of analytes it interacts with.

Detection of nitro-explosive compounds using derivatization and tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence

This thesis describes a novel approach towards the trace level detection of nitramine explosives, by exploring various reduction strategies and utilising ruthenium chemiluminescence. Synthesis of novel chemiluminescence compounds has been achieved, as well as the development of a detection method for determining the shelf life of ammunition.

New Compounds Bearing [M(S2O7)3]2– Anions (M = Si, Ge, Sn): Syntheses and Characterization of A2[Si(S2O7)3] (A = Na, K, Rb), A2[Ge(S2O7)3] (A = Li, Na, K, Rb, Cs), A2[Sn(S2O7)3] (A = Na, K), and the Unique Germanate Hg2[Ge(S2O7)3]Cl2 with Cationic 1∞[

The reaction of the group 14 tetrachlorides MCl4 (M = Si, Ge, Sn) with oleum (65 % SO3) at elevated temperatures led to the unique anionic complexes [M(S2O7)3]2– that show the central M atoms in coordination of three chelating S2O72– groups. The mean distances M–O within the complexes increase from 175 pm (M = Si) via 186 pm (M = Ge) up to 200 pm (M = Sn). The charge balance for the [M(S2O7)3]2– anions is achieved by alkaline metal ions A+ (A = Li, Na, K, Rb, Cs) which were implemented in the syntheses in form of their sulfates. The size of the A+ ions, i.e. their coordination requirement causes the crystallographic differences in the crystal structures, while the structure of the complex [M(S2O7)3]2– anions remains essentially unaffected. Furthermore, we were able to characterize the unique germanate Hg2[Ge(S2O7)3]Cl2 which forms when HgCl2 is added as a source for the counter cation. The Hg2+ and the Cl– ions form infinite cationic chains according to 1∞[HgCl2/2]+ which take care for the charge compensation. For selected examples of the compounds the thermal behavior has been monitored by means of thermal analyses and X-ray powder diffraction. For A being an alkaline metal the decomposition product is a mixture of the sulfates A2SO4 and the dioxides MO2, whereas Hg2[Ge(S2O7)3]Cl2 shows a more complicated decomposition. The tris-(disulfato)-silicate Na2[Si(S2O7)3] has additionally been examined by solid state 29Si and 23Na NMR spectroscopic measurements.

Rare earth 4-hydroxycinnamate compounds as carbon dioxide corrosion inhibitors for steel in sodium chloride solution

A series of rare earth 4-hydroxycinnamate compounds including Ce(4OHCin)3, La(4OHCin)3, and Pr(4OHCin)3 has been synthesized and evaluated as novel inhibitors for carbon dioxide corrosion of steel in CO2-saturated sodium chloride solutions. Electrochemical measurements and surface analysis have shown that these REM(4OHCin)3 compounds effectively inhibited CO2 corrosion by forming protective inhibiting deposits that shut down the active electrochemical corrosion sites on the steel surface. Inhibition efficiency was found to increase in the order Ce(4OHCin)3 < La(4OHCin)3 < Pr(4OHCin)3 and with increase in inhibitor concentration up to 0.63 mM. Detailed insights into corrosion inhibition mechanism of these compounds in carbon dioxide environment are also provided.