Detection and quantification of residues in sheep exposed to trace levels of dietary zilpaterol HCl

Abstract

Study objectives were to determine zilpaterol residues in urine and tissues of sheep fed dietary zilpaterol HCl, at levels commensurate with feed contamination, using common and novel screening and quantitative analytical methods. Sheep (50.0 ± 2.7 kg) were offered feed (1.75 kg/d) containing 0.0075 (L), 0.075 (M), or 0.75 (H) mg kg −1 of zilpaterol for 12 days and were slaughtered with 0-day (L-0, M-0, H-0; n = 4 each) or 3-day (H-3; n = 4) withdrawal periods. Rapid immunochromatographic assays (ICA) consistently detected urinary zilpaterol (LOD = 1.7 ng mL −1) in L-0 (54.2%), M-0 (96.0%), and the H-0 (100%) treatment groups but only detected zilpaterol in tissues (LOD~2.4 ng g −1) from the H-0 group. Advanced MS-based technologies detected zilpaterol in some, but not all, tissues of M-0, H-0, L-0, and H-3 sheep. Analytical techniques commonly used to ensure compliance with show-animal rules, import/export guidelines, and regulatory statutes routinely detected residues in animals exposed to zilpaterol at doses insufficient to elicit growth responses.

The determination of β‐agonist residues in bovine tissues using liquid chromatography–tandem mass spectrometry

“…For example, the Korean MRLs for zilpaterol in bovine muscle and liver are 1 and 5 μg kg −1 , respectively. Every exporters should ensure that meat products meet the residue standards of importing countries (Smith, Shelver, Chakrabarty, & Hoffman, 2019). To solve marketing problems, some tolerance levels for zilpaterol residues in bovine tissues have been proposed by Joint FAO/WHO Expert Committee on Food Additives (JECFA) to CAC (Codex Alimentarius Commission, 2017).…”

Electrospray ionization rapid screening sans liquid chromatography column: A sensitive method for detection and quantification of chemicals in animal tissues and urine

“…These values were comparable with a few previously reported LODs and LOQs of zilpaterol in urine (0.1 and 0.4 ng/mL, respectively) and in tissues (0.1-0.2 ng/g and 0.5-1 ng/g, respectively) obtained using LC/MS/MS of samples after SPE-or QuEChERS-based cleanup. 19,37,38 Moreover, excellent correlation between the RS-ESI-MS and LC/MS/MS results (0.987) was obtained for zilpaterol in incurred sheep urine ( Figure 1B). Weighting Good agreement between the RS-ESI-MS and LC/MS/MS (r 2 = 0.956) results was also obtained for ractopamine analysis of pig kidney ( Figure 1C).…”

“…In contrast, zilpaterol was quantified in all four livers when assayed by LC/MS/MS, with concentrations ranging between 3.1 and 4.3 ng/g. 19 The LODs and LOQs of zilpaterol obtained by RS-ESI-MS from sheep urine were 0.48 and 1.60 ng/mL while those from tissues were 0.23-0.70 ng/g and 0.78-2.30 ng/g, respectively. These values were comparable with a few previously reported LODs and LOQs of zilpaterol in urine (0.1 and 0.4 ng/mL, respectively) and in tissues (0.1-0.2 ng/g and 0.5-1 ng/g, respectively) obtained using LC/MS/MS of samples after SPE-or QuEChERS-based cleanup.…”

“…Data were obtained from analyses conducted on four consecutive days using RS-ESI-MS and 1.0 -2.4 ng/g, respectively, while the concentrations determined using LC/MS/MS were in the range of 4.0-4.7, 1.0-1.5 and 1.8-2.1 ng/g, respectively. 19 In liver, zilpaterol was detected in only two sheep by RS-ESI-MS, each being less than the liver LOQ. In contrast, zilpaterol was quantified in all four livers when assayed by LC/MS/MS, with concentrations ranging between 3.1 and 4.3 ng/g.…”

“…17,19,27 Solid-phase extraction (SPE) as documented by Smith et al was used for LC/MS/MS analyses of urine and tissues of sheep fed zilpaterol. 19 Urine samples from cows injected with flunixin were diluted 1:10 (v/v) with acetonitrile and LC/MS/MS analyses were performed as reported by Shelver et al 27 5-Hydroxyflunixin (a metabolite of flunixin) was also determined from the same urine samples. 27 The ractopamine content in pig kidney was measured using the LC/MS/MS method described by Shelver and McGarvey.…”