Fast liquid chromatography/tandem mass spectrometry (highly selective selected reaction monitoring) for the determination of toltrazuril and its metabolites in food

Simultaneous Analysis of Nicarbazin, Diclazuril, Toltrazuril, and Its Two Metabolites in Chicken Muscle and Eggs by In-Syringe Dispersive Solid-Phase Filter Clean-Up Followed by Liquid Chromatography-Tandem Mass Spectrometry

Nicarbazin (NICA) and triazine anticoccidial drugs (diclazuril (DIZ) and toltrazuril (TOZ)) are the primary strategy for preventing and treating coccidiosis. To prevent the development of drug resistance and mitigate the potential chronic toxicity to humans resulting from prolonged exposure, a liquid chromatography-tandem mass spectrometry method with high reliability and sensitivity was developed to determine NICA, DIZ, TOZ, and its two metabolites in chicken muscle and eggs. Upon establishing the extraction conditions involving 10 mL of acetonitrile and 10 min of sonication, in-syringe dispersive solid-phase extraction with silica was performed in combination with n-hexane clean-up. The selection of isotope peaks of precursor ions and low-mass range scanning allowed the two transitions for the quantification of all compounds. The limits of detection for DIZ and NICA were both 0.1 μg/kg, and for TOZ and metabolites, they were 0.3 μg/kg; the limits of quantitation were 0.3 and 1 μg/kg, respectively. The linear range was 0.25-50 ng/mL with a correlation coefficient r > 0.999. The average recoveries at three spiking levels in muscle and eggs were 90.1-105.2% and 94.0-103.7% with the relative standard deviations of 3.0-8.1% and 3.1-14.4%, respectively. The precision, accuracy, and stability were evaluated by three quality control samples.

Multiclass Method for the Determination of Anthelmintic and Antiprotozoal Drugs in Livestock Products by Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

The objective of this study was to establish a multi-residue quantitative method for the analysis of anthelmintic and antiprotozoal drugs in various livestock products (beef, pork, and chicken) using ultra-high-performance liquid chromatography-tandem mass spectrometry. Each compound performed validation at three different levels i.e., 0.5, 1, and 2× the maximum residue limit according to the CODEX guidelines (CAC/GL 71-2009). This study was conducted according to the modified quick, easy, cheap, effective, rugged, and safe procedure. The matrix-matched calibrations gave correlation coefficients >0.98, and the obtained recoveries were in the range of 60.2%-119.9%, with coefficients of variation ≤32.0%. Furthermore, the detection and quantification limits of the method were in the ranges of 0.03-3.2 and 0.1-9.7 μg/kg, respectively. Moreover, a survey of residual anthelmintic and antiprotozoal drugs was also carried out in 30 samples of beef, pork, and chicken collected in Korea. Toltrazuril sulfone was detected in all three samples. Thus, our results indicated that the developed method is suitable for determining the anthelmintic and antiprotozoal drug contents in livestock products.

Multiple response optimization of a QuEChERS extraction and HPLC analysis of diclazuril, nicarbazin and lasalocid in chicken liver

A method for the simultaneous determination of three commonly used coccidiostats in chicken liver was developed, comprising a multi-residue QuEChERS (quick, easy, cheap, effective, rugged and safe) extraction step, and a liquid chromatography-ultra violet-fluorescence (HPLC-UV/FL) analysis. The QuEChERS extraction was optimized using an experimental design approach that includes a screening step to obtain the critical variables, an optimization step using multiple response surface analysis and the calculation of a desirability parameter. The optimized method was validated with fortified samples, reaching an average recovery of 91% and an overall precision of 5.5% (mean of three analytes at three levels). Limits of detection calculated on fortified samples were 20 µg kg^-1 for lasalocid, 15 µg kg^-1 for nicarbazin and 120 µg kg^-1 for diclazuril. These values resulted at least one order of magnitude lower than the maximum allowed residue limit (MRL) of the studied coccidiostats for chicken liver.

Determination of ethanamizuril, a novel triazine coccidiostat, in rat plasma by ultra-performance liquid chromatography system-tandem mass spectrometry and its application in a toxicological study

Ethanamizuril is a new triazine compound that has the potential to be a novel anticoccidial drug. Toxicological studies in experimental rats were performed to understand the safety profile of ethanamizuril for drug product development. In this study, a novel, selective and accurate ultra-performance liquid chromatography tandem mass spectrometry method has been developed for the determination of ethanamizuril concentrations in rat plasma. With 4-nitro-o-cresol as an internal standard, sample pretreatment involved a one-step extraction with acetonitrile of 100 μL plasma. The detection was carried out by electrospray ionization mass spectrometry in negative ion mode with selected ion recording. The standard curves were linear (r²  ≥ 0.999) over the concentration range of 0.1-100 μg/mL. The relative standard deviations of intra- and inter-day precisions were less than 8.4 and 8.87%, respectively. The mean extraction recovery of ethanamizuril from rat plasma was 97.68-102.57%. The method was fully validated and successfully applied to monitor plasma concentrations of ethanamizuril in a short-term toxicity study and two-generation reproduction toxicity study. The result of the study confirmed that the elimination of ethanamizuril in rats is slow.

Development of molecularly imprinted electrochemical sensor with reduced graphene oxide and titanium dioxide enhanced performance for the detection of toltrazuril in chicken muscle and egg

A molecularly imprinted electrochemical sensor for toltrazuril (TZR) detection based on molecularly imprinted polymers (MIPs) immobilized on reduced graphene oxide (rGO) and titanium dioxide (TiO₂) modified platinum (Pt) electrode surface was fabricated for the first time. The synergistic fast electron transfer ability, large electroactive surface area and high catalytic activity from rGO and TiO₂ contribute to amplify the electrochemical signal and consequently improve the sensitivity of the sensor. The cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) tests were used to evaluate the performance of the electrochemical sensor. The results showed that the electrochemical sensor possessed high sensitivity, good selectivity and anti-interference ability toward TZR. By using the DPV, the electrochemical sensor displayed a wide linear concentration range from 0.43 to 42.54 μg/L, with a limit of detection of 0.21 μg/L (S/N = 3). Moreover, the recoveries and relative standard deviations (RSD) were 85.0%-97.0% and 3.5%-6.4% at three concentration levels, respectively, implying that the established sensor is promising for the accurate detection of TZR at trace levels in chicken muscle and egg samples.

Veterinary drugs residues: a review of the latest analytical research on sample preparation and LC-MS based methods

The world population is increasing and there is a growing demand for food, leading to intensification of farming methods and a requirement for more coadjuvants. Potential high profits sometimes lead to fraudulent use of drugs and pesticides. Veterinary drugs in particular can pose a real risk to human health if their residues are allowed to enter the food chain. Parent drugs and their metabolites can occur in foodstuffs individually or as multicomponent mixtures with enhanced adverse effects. In order to protect consumer safety, the European Union has established lists of forbidden substances, maximum residue limits for authorised drugs and precise criteria for confirmation analyses and interpretation of the results. Due to their nature and potential danger, the 'best available technique' should always be applied. Following this principle, this review examines the procedures and techniques applied to monitoring pharmaceutical products of major concern (e.g. anthelmintics, NSAIDs, corticosteroids, coccidiostats) in foods of animal origin, discussing advances over the past five years and future trends in the field of food safety. Our goal was both to focus attention on this important topic and to provide a selection of the most relevant recent papers on drug residues in foodstuffs.

High Resolution/Accurate Mass Targeted Proteomics

Targeted proteomics has emerged as the predominant method for quantitative analyses of peptides to complement shotgun LC/MS studies. Targeted measurements are routinely performed using the technique of selected reaction monitoring (SRM) on triple quadrupole instruments. However, the approach suffers from limitations inherent to the SRM technique. First, the selectivity of measurements is often insufficient to effectively discriminate the analytes from the complex background commonly encountered in biological samples. Second, the number of peptides analyzed in one experiment remains limited. The recent development of high resolution/accurate mass instruments, in conjunction with various acquisition methods, has opened new avenues for quantitative proteomic studies. An overview of the analytical capabilities of a high resolution hybrid quadrupole–orbitrap instrument for quantitative applications is presented and discussed in this chapter. The measurements are performed either on precursor ions (selected ion monitoring mode) or on fragment ions (parallel reaction monitoring mode), which overcome, in many instances, the selectivity issue encountered in complex samples, as illustrated on various examples. It clearly demonstrates the potential of high resolution mass measurements for quantitative proteomic applications.

Determination of 20 coccidiostats in milk, duck muscle and non-avian muscle tissue using UHPLC-MS/MS

In this paper, methods were developed to measure coccidiostats in bovine milk, duck muscle and non-avian species. The methods were validated to the maximum levels and MRLs laid down in European Union legislation. A simple sample preparation procedure was developed for the isolation of coccidiostat residues from bovine, ovine, equine, porcine and duck muscle tissue, based on solvent extraction with acetonitrile and concentration. An alternative method had to be developed for milk samples based on the QuEChERS sample preparation approach because of the high water content in this matrix. Milk samples were adjusted to basic pH with sodium hydroxide and extracted by using a slurry of acetonitrile, MgSO4 and NaCl. Purified sample extracts were subsequently analysed by using UHPLC-MS/MS in a 13.2-min chromatographic run. It was found that the use of rapid polarity switching enabled both negatively and positively charged ions to be analysed from a single injection. By using this approach, solvent usage was reduced significantly and sample throughput improved. The method was validated for the analysis of 20 coccidiostats (arprinocid, clopidol, decoquinate, diclazuril, diaveridine, ethopabate, halofuginone, laidlomycin, lasalocid, maduramicin, monensin, narasin, nequinate, nicarbazin, robenidine, salinomycin, semduramicin, toltrazuril, toltrazuril sulphoxide and toltrazuril sulphone) in muscle and milk. The method is quantitative for toltrazurils, but it cannot be used for confirmation because only the precursor ion is monitored. Accuracy values for muscle ranged from 80% to 125%, while CCα ranged from 2.2 µg kg(-1) for clopidol to 122 µg kg(-1) for toltrazuril sulphoxide. Bovine milk accuracy ranged from 84% to 120% for all analytes except maduramicin, semduramicin and salinomycin, for which the values were higher. CCα values achieved ranged from 1.1 µg kg(-1) for arprinocid, nequinate and lasalocid to 27 µg kg(-1) for toltrazuril.

Determination of 20 coccidiostats in egg and avian muscle tissue using ultra high performance liquid chromatography-tandem mass spectrometry

A quantitative, comprehensive multiresidue method which includes 20 coccidiostat residues has been developed. The method described uses a simple one-step liquid extraction with acetonitrile to isolate analytes from both the polyether ionophore and chemical classes of coccidiostats. Subsequent to a further concentration step, samples were analysed via UHPLC-MS/MS. The method was validated according to the Commission Decision 2002/657/EEC in egg and avian muscle. The method permitted quantitative confirmation for 13 compounds below target concentrations, and screening for a further 7 compounds. Within-laboratory repeatability gave accuracy values in the range of 68-129%, while reproducibility ranged between 75 and 123%. Calibration ranges were typically 1-50 μg kg⁻¹, although higher ranges were used for dinitrocarbanilide, imidocarb and toltrazuril residues. A regression coefficient (R²) value of greater than 0.98 was obtained for all analytes. Precision results ranged from 2.3 to 19.7% CV for egg and from 2.6 to 23.6% CV in muscle. CCα was in the range from 1.13 μg kg⁻¹ (clopidol) to 179 μg kg⁻¹ (lasalocid) in egg. In muscle, CCα ranged from 2.25 μg kg⁻¹ (aprinocid) to 4579 μg kg⁻¹ (dinitrocarbanilide). CCβ was from 1.29 μg kg⁻¹ (clopidol) to 209 μg kg⁻¹ (lasalocid) in egg, and 2.58 μg kg⁻¹ (arprinocid) to 6060 μg kg⁻¹ (dinitrocarbanilide) in muscle. Limits of quantification were 1 μg kg⁻¹ for all compounds, except imidocarb and dinitrocarbanilide (10 μg kg⁻¹), and toltrazuril and metabolites (50 μg kg⁻¹).