Page Banner

United States Department of Agriculture

Agricultural Research Service


Location: Food and Feed Safety Research

Title: Simultaneous determination of mequindox, quinocetone, and their major metabolites in chicken and pork by UPLC-MS/MS

item Li, Yanshen
item Liu, Kaili
item Beier, Ross
item Cao, Xingyuan
item Shen, Jianzhong
item Zhang, Suxia

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2014
Publication Date: 3/26/2014
Publication URL:
Citation: Li, Y., Liu, K., Beier, R.C., Cao, X., Shen, J., Zhang, S. 2014. Simultaneous determination of mequindox, quinocetone, and their major metabolites in chicken and pork by UPLC-MS/MS. Food Chemistry. 160:171-179.

Interpretive Summary: Mequindox and quinocetone are new synthetic antibiotics that belong to the group quinoxaline-1,4-dioxides (QDs). The general group of QDs are widely used in animal husbandry because of their high antimicrobial activity. However, these compounds are associated with reports of toxicity. There is currently no known method that can analyze for more than one of these drugs or that also can analyze for a large array of metabolites. A metabolite is a substance produced by metabolism in a living organism. There are at least 11 major metabolites identified from the metabolism of mequindox and quinocetone. The work described here resulted in the development of an analytical confirmatory multi-residue method for the analysis of mequindox, quinocetone, and their 11 known metabolites in chicken and pork tissues. The method uses liquid chromatography to separate the chemicals and then it uses mass spectrometry to obtain a definitive ID of each chemical. Mass spectrometry is a technique used for the analysis of a substance in which the molecule is subjected to bombardment by high-energy electrons or atoms to cause ionization and fragmentation to give a series of ions in the gas phase that constitutes the fragmentation pattern observed by using a mass spectrometer. The obtained pattern is usually definitive for a particular chemical. This research may result in a fast definitive method to determine the pressure of mequindox, quinoxaline, and their methods.

Technical Abstract: This research presents a sensitive and confirmatory multi-residue method for mequindox (MEQ), quinocetone (QCT), and their 11 metabolites in chicken and pork samples. After extracted with acetonitrile-ethyl acetate, acidulated, and extracted again with ethyl acetate sequentially, each sample was purified with C18 solid phase extraction (SPE) cartridge. Analysis was carried out on an ultra-high performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) using positive multiple reaction monitor (MRM) mode. Limit of detection (LOD) was between 0.05 and 5.20 µg/kg, while limit of quantification (LOQ) was between 0.20 and 16.0 µg/kg. Mean recoveries ranged from 69.1 to 113.3% at spike levels, with intra-day relative standard deviation (RSD) less than 11.7% and inter-day RSD less than 17.4%. This developed procedure was reliable, sensitive, and suitable for the determination of all 13 target analytes in chicken and pork samples and will benefit the control of MEQ and QCT and facilitate further pharmacokinetic and residue studies of similar Quinoxaline-1,4-dioxide veterinary drugs.

Last Modified: 10/20/2017
Footer Content Back to Top of Page