Determination of olaquindox, carbadox and cyadox in animal feeds by ultra-performance liquid chromatography tandem mass spectrometry

Simultaneous Screening of 172 Veterinary Drugs by Modified QuEChERS-LC-MS/MS in TCM Galli Gigerii Endothelium Corneum

An analytical method was developed for the screening of 172 veterinary drugs in traditional Chinese medicine Galli Gigerii Endothelium Corneum by high-performance liquid chromatography tandem mass spectrometry. The samples were pretreated by a modified QuEChERS method. A Zorbax Eclipse plus C18 column (1.8 μm, 3.0 × 150 mm2, Agilent) was used for the separation of analytes by gradient elution. All analytes were detected by electrospray ionization mass spectrometry with multiple reaction monitoring mode. Good linearity with R ≥ 0.99 was exhibited for all analytes within the respective range. The recoveries of all monitored analytes ranged from 55.4 to 127.6% at three spiked levels (limit of quantitation-LOQ, 2-fold LOQ, 10-fold LOQ), with relative standard deviations <17.8%. The estimated LOQ levels were 0.2-20 μg/kg. The application of this method provides a reference for the safety control of traditional Chinese medicines.

Advances in Metabolism and Metabolic Toxicology of Quinoxaline 1,4-Di-N-oxides

Quinoxaline 1,4-di-N-Oxides (QdNOs) have been used as synthetic antimicrobial agents in animal husbandry and aquaculture. The metabolism and potential toxicity have been also concerns in recently years. The metabolism investigations showed that there were 8 metabolites of Carbadox (CBX), 34 metabolites of Cyadox (CYA), 33 metabolites of Mequindox (MEQ), 35 metabolites of Olaquindox (OLA), and 56 metabolites of Quinocetone (QCT) in different animals. Among them, Cb3 and Cb8, M6, and O9 are metabolic residual markers of CBX, MEQ and OLA, which are associated with N → O reduction. Toxicity studies revealed that QdNOs exhibited severe tumorigenicity, cytotoxicity, and adrenal toxicity. Metabolic toxicology showed that toxicity of QdNOs metabolites might be related to the N → O group reduction, and some metabolites exhibited higher toxic effects than the precursor, which could provide guidance for further research on the metabolic toxicology of QdNOs and provide a wealth of information for food safety evaluation.

Hydrophilic-interaction-based magnetically assisted matrix solid-phase dispersion extraction of carbadox and olaquindox in feeds

BACKGROUND

Carbadox and olaquindox have been banned from feeds since 1998 by the EU because of their mutagenic, photoallergic, and carcinogenic effects. Unfortunately, owing to their outstanding effect, they are frequently abused or misused in animal husbandry. There is an urgent need to develop a sensitive and reliable method for monitoring these drugs in animal feeds.

RESULTS

This work reported a new method of hydrophilic-interaction-based magnetically assisted matrix solid-phase dispersion (MMSPD) extraction coupled with reversed-phase liquid chromatography-mass spectrometry for simultaneous determination of carbadox and olaquindox in animal feeds. 3-Trimethoxysilylpropyl methacrylate (γ-MAPS)-modified attapulgite (ATP) was crosslinked with γ-MAPS-modified iron(II,III) oxide (Fe₃ O₄ ), 1-vinyl-3-(butyl-4-sulfonate) imidazolium (VBSIm), acrylamide (AM), and N,N'-methylene-bis(acrylamide) (MBA) to synthesize ATP@Fe₃ O₄ @poly(VBSIm-AM-MBA) particles. The resultant particles were characterized by scanning electron microscopy, energy dispersive spectrometer, transmission electron microscopy, vibrating sample magnetometer, and Fourier transform infrared spectroscopy. Crosslinking of ATP into the magnetic particles has significantly increased the adsorption capacity of the particles. Under optimum conditions, the limits of detection (S/N = 3) were 0.3 μg kg^-1 and 0.9 μg kg^-1 for carbadox and olaquindox respectively. The intra-day and inter-day recoveries of the spiked targets in feed samples were in the range 83.5-98.3% with relative standard deviations of 1.0-8.3%.

CONCLUSION

With a simplified procedure and a low amount of sample, the proposed hydrophilic-interaction-based MMSPD method is not only useful for the determination of carbadox and olaquindox in feeds but also holds great promise for the analysis of other polar targets in solid or semisolid matrices. © 2021 Society of Chemical Industry.

Facile synthesis of highly luminescent rod-like terbium-based metal-organic frameworks for sensitive detection of olaquindox

Olaquindox (OLA), a chemically synthesized antibacterial growth promoter, despite being strictly controlled, is illegally used in feed to improve feed conversion efficiency and increase the rate of weight gain for animals. However, it has become clear that OLA has toxic effects on human beings via the transmission of OLA through the food chain. Here, by employing terbium nitrate to provide metal ions and benzene-1,3,5-tricarboxylic acid (H₃BTC) as an organic ligand, a simple, rapid, and easy scale-up synthetic method was presented for the fabrication of water-stable and highly luminescent rod-like metal-organic frameworks (Tb-BTC MOFs). Using the Tb-BTC MOFs as a luminescent probe, the luminescence quenching effect was obviously observed upon the addition of OLA, ascribed to the binding of OLA molecules on the surface of Tb-BTC and the existence of an inner-filter effect (IFE) mechanism. The correlation between the luminescence quenching ΔI and the concentration of OLA was found to be linear from 1.0 to 1000.0 μM with a detection limit of 20.6 nM. Furthermore, a Tb-BTC-loaded fiber paper was prepared and it is highly responsive (30 s) and suitable for visual OLA assay. The method described here can be successfully applied to the detection of OLA in animal feed and edible animal tissue samples.

Simultaneous determination of olaquindox, oxytetracycline and chlorotetracycline in feeds by high performance liquid chromatography with ultraviolet and fluorescence detection adopting online synchronous derivation and separation

Olaquindox, oxytetracycline and chlorotetracycline were widely used in feed as antibiotics and growth promoter to improve feed conversion efficiency and increase the rate of weight gain for animals. However, the use of these antibiotics in feed was gradually prohibited because of concerns about contamination and resistance in animals. A quantitative and confirmatory method for determining the presence of olaquindox, oxytetracycline and chlorotetracycline in feed by high performance liquid chromatography equipped with ultraviolet detector in series with fluorescence detector (HPLC-UVD-FLD) was developed, optimized, and validated in three different matrices (compound, concentrated and premix feed). The analytes extraction was performed with a mixture of acetonitrile and 0.1 mol/L ethylenediamine tetraacetic acid disodium-Mcllvaine buffer (1:4, v/v) by one step sample preparation procedure. The validated method presented a broad linear range and good linearity with weighted least square method. The decision limit of the analytes ranged from 0.61 to 0.77 mg/kg for olaquindox, 0.90 to 1.2 mg/kg for oxytetracycline and 1.3 to 2.0 mg/kg for chlorotetracycline. The average recovery values found in intermediate precision conditions were ranged from 88.0 to 99.7% for olaquindox with RSD lower than 11.1%, from 84.4 to 99.0% for oxytetracycline with RSD lower than 9.6%, from 83.8 to 97.5% for chlorotetracycline with RSD lower than 10.0%. By Youden test and bottom-up method, the method was proved to be sufficiently robust and had a small uncertainty for different concentration levels. The developed method was successfully utilized for commercial feed samples to monitor complex cross contamination and residue conditions. Online synchronous derivation and separation using ultraviolet detector in series with fluorescence detector can effectively prevent false positive of chlorotetracycline in feed caused by vegetable meal. Since olaquindox, oxytetracycline and chlorotetracycline are widely used in feed, the developed method provide an important and analytical tool for the simultaneous identification and quantification of them in feed to monitor its risk of cross contamination and excessive content.

Tracing major metabolites of quinoxaline-1,4-dioxides in abalone with high-performance liquid chromatography tandem positive-mode electrospray ionization mass spectrometry

BACKGROUND

Owing to the comprehensive application of quinoxaline-1,4-dioxides (QdNOs) in aquaculture, QdNOs and metabolites are often detected in marine food, including abalone. QdNOs are reported to exhibit cytotoxicity, photoallergy, mutagenicity, and carcinogenicity activities. To monitor for contamination of QdNOS in abalone and assess dietary exposure, a simple and reliable analytical method for the detection of QdNOs and their major metabolites was developed.

RESULTS

This work is the first to present a simple and fast pretreatment procedure coupled with high-performance liquid chromatography tandem positive-mode electrospray ionization mass spectrometry (LC-MS/MS) for tracing of major metabolites of QdNOs in abalone. Extraction steps were simplified by the use of methanol and ethyl acetate containing 0.1% formic acid instead of more complicated acidolysis and enzymolysis pretreatment procedures. High-sensitive characters were obtained with limits of detection ranged from 0.16 to 2.1 μg kg^-1 for QdNOs and their major metabolites.

CONCLUSION

These results indicate that the LC-MS/MS method developed could be applied for QdNOs and major metabolites detection in actual samples. Considering the large production and consumption of abalone in Shandong Province, China, this work will also contribute to the further understanding of the often-ignored exposure pathway of QdNOs. © 2019 Society of Chemical Industry.