Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2018
Publication Date: 10/8/2018
Citation: Chakrabarty, S., Shelver, W.L., Hakk, H., Smith, D.J. 2018. Atmospheric solid analysis probe and modified desorption electrospray ionization mass spectrometry for rapid screening and semi-quantification of zilpaterol in urine and tissues of sheep. Journal of Agricultural and Food Chemistry. 66(41):10871-10880. https://doi.org/10.1021/acs.jafc.8b03925.
Interpretive Summary: Zilpaterol is a ß-adrenergic feed additive that produces leaner meat, improves growth rates, and decreases feed consumption in livestock. Although zilpaterol use in cattle diets has been approved in North and Central America and in South Africa, its use is strictly banned by the European Union, China and most other countries. Because zilpaterol use is legal in only a few countries, the rapid and sensitive detection of zilpaterol in live animals or in animal tissues is of interest to regulatory and trade officials worldwide. In this report, two sensitive mass-spectrometry based assays were developed that allow the rapid, sensitive, and semi-quantitative screening of zilpaterol in animal urine and tissues in about 30 seconds per sample. Little to no sample preparation was necessary and the assay was validated using standard techniques to reliably detect low concentrations of zilpaterol. The study demonstrates that mass-spectrometry based assays have the potential for field uses in which near real time detection of drug residues is necessary. The techniques have the potential to be used for numerous other chemical residues of importance to animal agriculture.
Technical Abstract: Ambient ionization mass spectrometric methods including desorption electrospray ionization (DESI) and atmospheric solid analysis probe (ASAP) have great potential for applications requiring real-time screening of target molecules in complex matrices. Such techniques can also rapidly produce repeatable semi-quantitative data, with minimal sample preparation, relative to liquid chromatography-mass spectrometry (LC-MS). In this study, a commercial ASAP probe was used to conduct both ASAP-MS and DESI-like MS analyses. We conducted real-time qualitative and semi-quantitative analysis of the leanness-enhancing agent zilpaterol in incurred sheep urine, kidney, muscle, liver and lung samples using ASAP-MS and DESI-like MS. Using ASAP, limits of detection (LoD) and quantitation (LoQ) in urine were 1.1 and 3.7 ng/mL, respectively, while for DESI-like MS they were 1.3 and 4.4 ng/mL, respectively. The LoDs for tissues were 0.1 - 0.4 ng/g using ASAP, and 0.2 - 0.6 ng/g with DESI-like MS. The LoQs of the tissues in ASAP were 0.4 - 1.2 ng/g and 0.5 - 2.1 ng/g in DESI-like MS. Trace levels of zilpaterol were accurately analyzed in urine and tissues of sheep treated with dietary zilpaterol HCl. The correlation coefficient (R2) between semi-quantitative ASAP-MS and DESI-like MS results of urine samples was 0.872. The data from ASAP and DESI-like MS were validated using LC-MS/MS; urinary zilpaterol concentrations '5.0 ng/mL or tissue zilpaterol concentrations '1.5 ng/g were detected or quantified in ASAP and DESI-like MS respectively, 100% of the time. Forty samples could be analyzed in triplicate, directly from biological matrices in under an hour.