METABOLIC VARIABLES AFFECTING THE EFFICACY, SAFETY, AND FATE OF AGRICULTURAL CHEMICALS
Location: Animal Metabolism-Agricultural Chemicals Research
Title: Chlorate analyses in matrices of animal origin
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 13, 2011
Publication Date: February 7, 2011
Citation: Smith, D.J., Taylor, J.B. 2011. Chlorate analysis in matrices of animal origin. Journal of Agricultural and Food Chemistry. 59:1598-1606.
Interpretive Summary: Chlorate is being developed for use as a food-safety tool due to their activity against pathogens such as Salmonella and E. coli O157:H7 in economically important species such as swine, cattle, and poultry. Because chlorate is active against Salmonella, it may also have benefits for use in young sheep that are susceptible to the pathogen. In order to develop chlorate into a useful, and safe animal husbandry tool, experiments investigating its activity and its mechanisms action must be conducted. Such studies require that methods for the measurement of chlorate in a variety of tissues, body fluids, and excreta be available. However methods for chlorate analysis are not generally available for dirty matrices such as feces, intestinal fluids, and urine and are not available for other matrices such as serum, milk, and tissues. The goal of this study was to develop methods of chlorate analysis that would support a variety of studies in which chlorate measurement is required. To this end, mass spectral, colorimetric, and ion chromatographic methods of chlorate analysis were developed that are able to quantitatively measure chlorate over wide concentration ranges in matrices of physiological interest.
Sodium chlorate is being developed as a potential food-safety tool for use in the livestock industry because of its effectiveness at decreasing concentrations of certain Gram-negative pathogens in gastrointestinal tracts of food animals. A number of studies with sodium chlorate in animals have demonstrated that concentrations of chlorate in meat, milk, wastes, and gastrointestinal contents range from parts per billion to parts per thousands, depending upon chlorate dose, matrix, and time lapse after dosing. Although a number of analytical methods exist for chlorate salts, very few were developed for use in animal-derived matrices and none have anticipated the range of chlorate concentrations that have been observed in animal wastes and products. To meet the analytical needs of our development work, LC-MS/MS, ion chromatographic, and colorimetric methods were developed to measure chlorate residues in a variety of matrices. The LC MS/MS method utilizes a Cl18O3- internal standard and is applicable to a variety of matrices and provides quantitative assessment of samples from 0.050 to2.5 ppm. Due to ion-suppression, matrix-matched standard curves are appropriate when using LC MS/MS to measure chlorate in animal-derived matrices. A colorimetric assay based on the acid catalyzed oxidation of o-tolidine proved valuable for measuring 20 ppm or greater quantities of chlorate in blood serum and milk, but not urine samples. Ion chromatography was useful for measuring chlorate residues in urine and in feces when chlorate concentrations exceeded 100 ppm, but no effort was made to maximize ion-chromatographic sensitivity. Collectively, these methods offer the utility of measuring chlorate in a variety of animal-derived matrices over a wide range of chlorate concentrations.