This paper describes research relating to the major recall of pet food that occurred in Spring 2007 in North America. Clinical observations of acute renal failure in cats and dogs were associated with consumption of wet pet food produced by a contract manufacturer producing for a large number of companies. The affected lots of food had been formulated with wheat gluten originating from China. Pet food and gluten were analyzed for contaminants using several configurations of high-performance liquid chromatography (HPLC) and mass spectrometry (MS), which revealed a number of simple triazine compounds, principally melamine and cyanuric acid, with lower concentrations of ammeline, ammelide, ureidomelamine, and N-methylmelamine. Melamine and cyanuric acid, have been tested and do not produce acute renal toxicity. Some of the triazines have poor solubility, as does the compound melamine cyanurate. Pathological evaluation of cats and dogs that had died from the acute renal failure indicated the presence of crystals in kidney tubules. We hypothesized that these crystals were composed of the poorly soluble triazines, a melamine-cyanuric acid complex, or a combination. Sprague dawley rats were given up to 100 mg/kg ammeline or ammelide alone, a mixture of melamine and cyanuric acid (400/400 mg/kg/day), or a mixture of all four compounds (400 mg/kg/day melamine, 40 mg/kg/day of the others). Neither ammeline nor ammelide alone produced any renal effects, but the mixtures produced significant renal damage and crystals in nephrons. HPLC-MS/MS confirmed the presence of melamine and cyanuric acid in the kidney. Infrared microspectroscopy on individual crystals from rat or cat (donated material from a veterinary clinic) kidneys confirmed that they were melamine-cyanuric acid cocrystals. Crystals from contaminated gluten produced comparable spectra. These results establish the causal link between the contaminated gluten and the adverse effects and provide a mechanistic explanation for how two apparently innocuous compounds could have adverse effects in combination, that is, by forming an insoluble precipitate in renal tubules leading to progressive tubular blockage and degeneration.

SoRd-phase microextraction (SPME) Is an Inexpensive, rapid, and solvent-free extraction method for the Isolation of organic compounds from an aqueous sample. The technique uses a few centimeters of poly(dlmethylslk>xane)-coated fused silica optical fiber which Is mounted for convenience and ruggedness Into a microsyringe. The organic contaminants are extracted Into the coating and transferred for thermal desorption and analysis Into the Injector of a gas chromatograph. Mathematical descriptions of the absorption and desorption processes were developed and compared with experimental results. One model assumes a perfectly agitated solution which results In extraction times dependent only on diffusion of analyte In the coating. The second model considers extraction from a static solution. In this case extraction times are determined by difusión of analyte In water. These models facilitate a better understanding of the extraction process. Results Indcate that when standard stirring equipment Is used as a means of agitation, the dynamics of the extraction process Is controMed by difusión of analyte through the thin static aqueous layer located around the fiber. Extraction times for benzene, toluene, and p-xylene using a coating thickness of 55 µ are under 10 min and can be shortened substantially when more efficient agitation methods are used. The technique allows sub-ppb determination of organics In water with flame Ionization detection. The linear range of the method Is over several orders of magnitude. The sensitivity of the technique Is dependent on the coating volume and the coat-Ing/water distribution constant. The relative precision of the method Is a few percent and Is dependent on the thickness of the coating. Using this technique, poly(dlmethylslloxane)/water distribution constants were determined for benzene (125), toluene (294), and p-xylene (831) and are similar to corresponding values for octanol/water distribution constants.

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SummarySolid Phase Micro Extraction (SPME) involves exposing a fused silica fiber coated with stationary phase to a contaminated water sample. The organic analytes become partitioned between the stationary phase and the water and when equilibrium is reached the fiber is removed from the solution and the analytes are thermally desorbed in the injector of a gas chromatograph.The fiber is contained in a syringe to facilitate handling.Factors which affect linear range, limit of detection, and total analysis time are discussed with regard to the development of a method for analysis of volatile compounds in environmental water samples.The sensitivity of the method was determined by the thickness of the film of stationary phase; the equilibration time, however, increased with the film thickness, although it can be minimized by use of a cross-shaped stirrer bar.Increasing the thickness of stationary phase in the analytical column enables the cryofocusing temperature to be increased from -40 to -15°C. With an ion trap mass spectrometer, detection limits required by the US Environmental Protection Agency are met for all compounds except chloromethane and chloroethane. The method has been applied to environmental water samples.

Molecular and atomic radicals from electron-impact dissociation of methane and a variety of fluoroalkanes are detected mass spectometrically as organotellurides produced by the reaction of the radicals at the surface of a tellurium mirror. The radicals detected include CH3 from CH4; CF3 from CF4 and CHF3; CHF2 from CHF3 and CH2F2; CH2F from CH3F; and CF3 and C2F5 from C2F6 and C3F8 produced by electron impact at energies between 10 eV and 500 eV. Relative cross sections are measured. These are placed on an absolute scale by comparison with related measurements. For the collision energies relevant to processing plasmas, 10–30 eV, it is shown that dissociation into neutrals rather than dissociative ionization is mainly responsible for the production of molecular radicals.