Chlorate Analyses in Matrices of Animal Origin

Abstract

Sodium chlorate is being developed as a potential food-safety tool for use in the livestock industry because of its effectiveness in decreasing concentrations of certain Gram-negative pathogens in the 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 thousand, 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 this development work, LC-MS, ion chromatographic, and colorimetric methods were developed to measure chlorate residues in a variety of matrices. The LC-MS method utilizes a Cl(18)O(3)(-) internal standard, is applicable to a variety of matrices, and provides quantitative assessment of samples from 0.050 to 2.5 ppm. Due to ion suppression, matrix-matched standard curves are appropriate when using LC-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 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.

Effect of intravenous or oral sodium chlorate administration on the fecal shedding of Escherichia coli in sheep1,2

“…Blood and fecal serum chlorate was determined using liquid chromatography mass spectrometry as described by Smith and Taylor (2011). Briefly, the mass spectral method used an 18 O-labeled internal standard (Smith and Taylor, 2011) and a matrix-matched calibration curve.…”

“…Blood and fecal serum chlorate was determined using liquid chromatography mass spectrometry as described by Smith and Taylor (2011). Briefly, the mass spectral method used an 18 O-labeled internal standard (Smith and Taylor, 2011) and a matrix-matched calibration curve. Serum assay volumes for mass spectral analyses were 0.2 mL with a cor-responding method limit of quantification of 0.067 µg/mL; less serum sample was used during repeat analyses for samples whose concentrations exceeded the range of the standard curve during an initial analysis.…”

“…Fecal samples that returned chlorate values greater than the highest standard of the standard curve were re-run with lesser amount of samples. Because of relatively high concentrations of chlorate, serum samples collected at 4 and 8 h were assayed using the colorimetric procedure described by Smith and Taylor (2011).…”

Risks for public health related to the presence of chlorate in food

“…In complex matrices of animal origin, liquid chromatography-mass spectrometry (LC-MS) utilizing a Cl 18 O 3 -internal standard has been demonstrated to be applicable to sensitively quantify chlorate (Smith and Taylor, 2011). In foods of plant origin chlorate is recommended to be analysed by a multiresidue method for polar pesticides (Quick Polar Pesticides Method, QuPPe).…”

Chlorate and Other Oxychlorine Contaminants Within the Dairy Supply Chain

“…LC‐MS/MS methodology has also been developed to analyze perchlorate residues in several animal matrices including dairy (Capuco et al., ; Dodds, Kennish, von Hippel, Bernhardt, & Hines, ; Kirk, Smith, Tian, Anderson, & Dasgupta, ). This method was analyzed on a matrix by matrix basis by Smith and Taylor (), who were capable of detection of chlorate at 500 μg/L for milk samples. There are some reports of mixed mode separation for the analysis of chlorates and perchlorate, some of which employ MS or MS/MS‐based detection (Hepperle et al., ; Watanabe & Matsumoto, ).…”