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.

An approach has been developed to characterize the individual chemical constituents of botanicals. The challenge was to identify and quantitate the significant analytes in these complex mixtures, largely in the absence of authentic standards. The data-rich information content generated by this three-detector configuration was specifically intended to be used to conduct safety and/or quality evaluations for complex botanical mixtures, on a chemical constituent basis. The approach utilized a broad gradient UHPLC chromatographic separation. Following the chromatographic separation and UV detection, the eluent was split and sent into a charged aerosol detector (CAD), for quantitation, and a quadrupole/time-of-flight high-resolution mass spectrometer for component identification. The known bias of the otherwise universal CAD response, for organic solvent composition of the mobile phase, was compensated by the addition of an inverse gradient make-up stream. This approach and the orthogonal information content from the chromatography and three different detectors was specifically designed to enable in-silico safety assessments. These guide, minimize, or even eliminate the need for in vivo and in vitro safety assessments. The methodology was developed and demonstrated using standardized extracts of Ginkgo biloba. Results from the development of this novel approach and the characterization example reported here demonstrate the suitability of this instrumental configuration for enabling in-silico safety assessments and proving general quality assessments of botanicals.Electronic supplementary materialThe online version of this article (10.1007/s00216-018-1163-y) contains supplementary material, which is available to authorized users.

Improvements to the design and operation of a Gilson 215 multiprobe liquid-handling system have resulted in a significant increase in the throughput for flow injection molecular weight characterization of combinatorial chemistry libraries. The rapid injection sequence, and subsequent increased sample throughput, is effected by directing the entire mobile-phase flow through each of the injection loops sequentially while isolating or "dead-ending" the remaining nonactive loops. This mode of operation was accomplished by incorporating column-switching valves prior to and following the set of eight parallel injectors. Analysis rates are achieved without sacrificing the integrity of the flow injection peak profile as baseline resolution is maintained for all samples. Using this system, the total analysis time for a 96-well microtiter plate has been reduced to approximately 5 min.

A crucial step in the isolation of antibiotic substances is establishing whether or not the isolated material represents a new chemical entity. Because of the importance of molecular weight to this process-known as dereplication-mass spectrometry has traditionally played an active role. In this communication a strategy for utilizing liquid chromatography-mass spectrometry (LC/MS) for novelty assessment is described. Crude extracts (20-50 µg) are chromatographed by conventional bore high-performance liquid chromatography (1 mL/min) after which a postcolumn split to divert roughly one-tenth of the sample to the mass spectrometer for molecular weight determination by electrospray ionization (ESI) mass spectrometry. The majority of the effluent is sent to a UV detector and ultimately collected as 1-min fractions for biological testing. As a secondary confirmation of molecular weight, an aliquot of each fraction (< 5%) is taken for analysis by matrix-assisted laser desorption ionization (MALDI). The improved efficiency of this approach over more traditional schemes utilizing off-line fraction collection and conventional ionization methods can be explained by several factors. First, the superior sensitivity of ESI and MALDI means that less material is required for successful analysis. Second, on-line LC/MS optimizes the efficiency of sample transfer and saves both time and labor. Furthermore, the concentration dependence of ESI allows a majority of the material injected for LC/MS to be recovered for biological testing without compromising the signal available for molecular weight determination. As a validation of the above method, crude extracts containing two well-characterized antibiotics-teicoplanin and phenelfamycin-were examined. Results from these analyses are presented along with data from the analysis of a potent unknown antifungal sample.

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