We present preliminary results of a VAMAS interlaboratory study on organic depth profiling, TWA2, sub-project A3 (d). A layered organic system was used to assess the repeatability and comparability of organic depth profiling. Nineteen respondents have provided sufficient data to demonstrate that the coefficients of variation for depth resolution, sputtering yield and relative secondary ion intensities are typically 5-10%. This can be as good as 2-3% with modern instruments, when using a stable sputtering ion current and careful procedures, which approaches the limits set by the samples themselves. The respondents have also demonstrated three methods to improve the quality of depth profiling for this system, namely, sample rotation, cooling to at least −80• C and grazing incidence angles for the sputtering ion.

Ten years of field data from an Oklahoma drinking water utility were analyzed for the effects of an acid-stabilized, ionic copper algaecide/bactericide called EarthTec on geosmin concentrations in the water traveling by pipeline from the source lake to a water treatment plant. The data show that geosmin already present in the raw water is reduced more during periods of applying algaecide than when not. Median reduction in geosmin concentration from pipe intake to pipe outfall by natural degradation without addition of algaecide was 5.6 ng/L removed (56.7% reduction) and improved to 126 ng/L removed (83% reduction) during periods the algaecide was being dosed at 1 μL/L, equivalent to 0.06 mg/L as copper. A laboratory study to replicate the phenomenon at bench-scale showed that either the algaecide itself or its copper-free acidic carrier can be used to depress pH and drive a reaction converting geosmin to an odorless dehydration product, argosmin. Algaecides intuitively reduce the organisms that produce geosmin, but this study shows that geosmin already present in the water is also being reduced through chemical conversion to the odorless argosmin, representing a novel means of geosmin removal in drinking water.

DO I 4HN1 : 1 and 2 : 1 products formed by nucleophilic attack of ammonia in liquid ammonia solutions of 1,3,5trinitrobenzene and of 2,4,6-trinitrotoluene have been observed by 13C n.m.r. spectroscopy. In the latter reaction three 2: 1 products are observed: two geometrical isomers formed by attack at the 1and 3position of 2,4,6-trinitrotoluene and a structural isomer formed by attack at the 3and 5-position.Ammonia behaves as a nucleophile towards a-electron-deficient molecules such as 1,3,5-trinitrobenzene (TNB) and 2,4,6trinitrotoluene (TNT) especially when these molecules are dissolved in the effective ionising solvent liquid ammonia. There is extensive evidence that, at least in the case of TNB, the initial step is the formation of the zwitterion (1) followed by deprotonation by a second molecule of ammonia to form the anionic species (2) (Scheme). The product is a typical Jackson '-Meisenheimer (o-anionic) compound." An earlier ' H n.m.r. study ' of the TNB-liquid ammonia system had shown that, at 220 K, the initial formation of (2) was rapidly followed by almost complete conversion into (3). Only one of the two possible geometrical isomers represented by (3) was observed. From the 'H n.m.r. absorption spectra, it was apparent that the formation of (3) from (2) was reversible, although at 240 K the equilibrium was still in favour of (3). No free TNB was observed.A corresponding 'H n.m.r. study l o of the products formed by dissolving TNT in liquid ammonia produced rather similar results. However, the general Scheme, with the formation of (4) and (S), both geometrical isomers of (6), was observed. In those experiments the structural isomer (7) was not detected.We have now restudied both systems using 13C n.m.r. spectroscopy.

Proton n.m.r. spectra of the solutions formed by dissolving various polynitro-and substituted polynitro-benzenes in liquid ammonia have been measured. Products, with Meisenheimer-like structures, formed by nucleophilic attack of NH,-on the solutes have been identified. In a number of cases, attack by a second NH,-ion occurs. Some of the products show geometrical isomerism. With 2,4,6-trinitrotoluene there is no evidence for the formation of the carbanion formed by loss of a proton from the methyl group of 2,4,6-trinitrotoluene.

The association of Ag+ with benzene in aqueous solution has been estimated from measurements of the chemical shift of the benzene resonance in the presence of varying excess concentrations of silver nitrate. The results are consistent with the formation of a 1 : 1 complex and a 2 : 1 complex between Ag+ and benzene. The numerical values of the equilibrium quotients agree well with earlier values obtained from solubility measurements.