Identification of an unknown beta-agonist in feed by liquid chromatography/bioassay/quadrupole time-of-flight tandem mass spectrometry with accurate mass measurement

A novel tool to screen for treatments with clenbuterol in bovine: Identification of two hepatic markers by metabolomics investigation

Surveillance of illegal use of growth promoters such as β₂-agonists in food producing animals rely on the detection of drug residues by LC-MS/MS. Screening strategies focusing on indirect physiological responses following administration of active compounds are promising approaches to strengthen existing targeted methods and ensure food safety. A metabolomics analysis based on LC-HRMS was carried out on liver extracts from bulls experimentally treated with clenbuterol combined with dexamethasone (n = 8) to mimic a potential anabolic practice, and control animals (n = 8). Nicotinic acid and 5'-deoxy-5'-methylthioadenosine were identified as biomarkers of treatment. Ratio values of such markers to others of the same metabolic pathways (nicotinamide or methionine) were used to develop a classification model to assign animals as treated with clenbuterol or non-treated. The classification model was tested on an external validation set comprising 74 animals either treated with different anabolic compounds (β₂-agonists, sexual steroids, corticosteroid), or non-treated, showing 100% sensitivity and specificity.

Isobaric Tags for Relative and Absolute Quantification (iTRAQ)-Based Untargeted Quantitative Proteomic Approach To Identify Change of the Plasma Proteins by Salbutamol Abuse in Beef Cattle

Salbutamol, a selective β₂-agonist, endangers the safety of animal products as a result of illegal use in food animals. In this study, an iTRAQ-based untargeted quantitative proteomic approach was applied to screen potential protein biomarkers in plasma of cattle before and after treatment with salbutamol for 21 days. A total of 62 plasma proteins were significantly affected by salbutamol treatment, which can be used as potential biomarkers to screen for the illegal use of salbutamol in beef cattle. Enzyme-linked immunosorbent assay measurements of five selected proteins demonstrated the reliability of iTRAQ-based proteomics in screening of candidate biomarkers among the plasma proteins. The plasma samples collected before and after salbutamol treatment were well-separated by principal component analysis (PCA) using the differentially expressed proteins. These results suggested that an iTRAQ-based untargeted quantitative proteomic strategy combined with PCA pattern recognition methods can discriminate differences in plasma protein profiles collected before and after salbutamol treatment.

Identification of Buctopamine and Mebuctopamine, a β2 Receptor Agonist and Its Metabolite, in Swine Hair and Feed Additives

4-[2-(t-Butylamino)-1-hydroxyethyl]phenol (buctopamine, 4), a new β₂ receptor agonist (β₂-agonist), was found to be an adulterant in feed additives for swine in Taiwan, where using β₂-agonists in food-production animals is prohibited. Buctopamine and its metabolite, 4-[2-(t-butylamino)-1-hydroxyethyl]-2-methoxyphenol (mebuctopamine, 2), were detected in swine hair specimens. Authentic compounds 2 and 4 were synthesized with 98.6% and 97.7% purity, respectively, as reference standards for analysis, and both compounds were more hydrophilic than ractopamine and clenbuterol. In a preliminary pharmacological evaluation, compounds 2 and 4 exhibited moderate human β₂ receptor binding affinity and did not show significant affinities for the human α₁, α₂, β₁, and β₃ receptors. After addition of compounds 2-4 into the β₂-agonist library, a multiresidue analysis of 26 β₂-agonists by using triple quadrupole LC/MS/MS for routine screening conducted by regulatory authorities was established, in which the common limits of quantification for the 26 β₂-agonists in swine feed and hair are 10 and 25 ng/g, respectively. In addition, the illegal use of buctopamine (4) has been effectively prevented. The results of this study are also useful for controlling the illegal use of new β₂-agonists in food-production animals.

Determination of multiresidue analysis of β-agonists in muscle and viscera using liquid chromatograph/tandem mass spectrometry with Quick, Easy, Cheap, Effective, Rugged, and Safe methodologies

The official analytical method of the Taiwan Food and Drug Administration, Ministry of Health and Welfare for testing for veterinary drug residues in foods is the multiresidue analysis of β-agonists. Samples are pretreated through liquid–liquid extraction and solid-phase extraction. This method is time consuming and requires the intensive use of solvents. To improve analytical efficiency and reduce costs, our study incorporated QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) techniques to establish a new method of multiresidue analysis of β-agonists in animal muscle and viscera. The pretreatment time was shortened and solvent usage was minimized. The modified analysis was conducted using liquid chromatography/tandem mass spectrometry (LC–MS/MS) and quantification was performed using multiple reaction monitoring. The results demonstrated that the correlation coefficients of the tissue calibration curve were higher than 0.99 and the limit of quantification (LOQ) was 1 ppb. The average recoveries in spiked samples varied from 70% to 120%, and the relative difference between duplicated analysis results was lower than 10%. On the basis of the results, the proposed method was concluded to be an appropriate procedure for determining the presence of β-agonists, and demonstrated the advantages of high recovery rates in spiked samples, high precision, reduced analysis time and solvent usage, and lower costs.

Multiresidue Method for Analysis of β Agonists in Swine Urine by Enzyme Linked Receptor Assay Based on β2 Adrenergic Receptor Expressed in HEK293 Cells

A novel enzyme-linked receptor assay (ELRA) based on β₂-adrenergic receptor (β₂-AR) has been developed for rapid and high-throughput detection of β-adrenergic agonists (β-agonists) in urine. Human embryonic kidney cells (HEK293) were introduced as the expression system to enhance the functionality of the recombinant β₂-AR, and the attempt to detect β-agonists in swine urine using such approaches was accomplished unprecedentedly. In this article, a recombinant porcine β₂-AR was produced in the inner membrane of HEK293 cells and purified from crude membrane protein by nickel-nitrilotriacetic acid affinity chromatography. After activity identification, the recombinant receptor was used in the development of direct competitive ELRA. Several parameters such as blocking buffer and blocking process were optimized and the performance of the system was determined. The IC50 concentrations of clenbuterol, salbutamol, and ractopamine were 34, 53 and 63 μg/L, and the average recovery rates were 68.2%, 60.3% and 65.5%, respectively. ELRA based on β₂-AR shows a series of advantages such as safety, easy operation, and high efficiency, making it promising for the rapid screening of β-agonists in animal urine.

Sports doping: emerging designer and therapeutic β2-agonists

Beta2-adrenergic agonists, or β2-agonists, are considered essential bronchodilator drugs in the treatment of bronchial asthma, both as symptom-relievers and, in combination with inhaled corticosteroids, as disease-controllers. The use of β2-agonists is prohibited in sports by the World Anti-Doping Agency (WADA) due to claimed anabolic effects, and also, is prohibited as growth promoters in cattle fattening in the European Union. This paper reviews the last seven-year (2006-2012) literature concerning the development of novel β2-agonists molecules either by modifying the molecule of known β2-agonists or by introducing moieties producing indole-, adamantyl- or phenyl urea derivatives. New emerging β2-agonists molecules for future therapeutic use are also presented, intending to emphasize their potential use for doping purposes or as growth promoters in the near future.

The pivotal role of mass spectrometry in determining the presence of chemical contaminants in food raw materials

During recent years, a rising interest from consumers and various governmental organizations towards the quality of food has continuously been observed. Human intervention across the different stages of the food supply chain can lead to the presence of several types of chemical contaminants in food-based products. On a normal daily consumption basis, some of these chemicals are not harmful; however, for those that present a risk to consumers, legislation rules were established to specify tolerance levels or in some cases the total forbiddance of these specific contaminants. Hence, the use of appropriate analytical tools is recommended to properly identify chemical contaminants. In that context, mass spectrometry (MS)-based techniques coupled or not to chromatography offer a vast panel of features such as sensitivity, selectivity, quantification at trace levels, and/or structural elucidation. Because of the complexity of food-based matrices, sample preparation is a crucial step before final detection. In the present manuscript, we review the contribution and the potentialities of MS-based techniques to ensure the absence of chemical contaminants in food-based products.

Cetirizine as pH-dependent cross-reactant in a carbamazepine-specific immunoassay

High performance liquid chromatography (HPLC) was hyphenated with a previously reported carbamazepine-specific enzyme-linked immunosorbent assay (ELISA) as a screening approach to water analysis in order to identify possible interferences from transformation products. Treated wastewater was analysed and three substances were recognized by the antibody besides carbamazepine: the metabolites 10,11-dihydro-10,11-epoxycarbamazepine and 2-hydroxycarbamazepine plus the structurally not obviously related antihistamine cetirizine. The molar cross-reactivity against cetirizine was found to be pH-dependent and assessed to be 400% at pH 4.5 and 22% at pH 10.5. Performing the ELISA at pH 10.5 greatly improved the accuracy when carbamazepine was determined in surface and wastewater samples.

Hormonal growth promoting agents in food producing animals

In contrast to the use of hormonal doping agents in sports to enhance the performance of athletes, in the livestock industry hormonal growth promoters ("anabolics") are used to increase the production of muscle meat. This leads to international disputes about the safety of meat originating from animals treated with such anabolics.As a consequence of the total ban in the EU of all hormonal active growth promoters ("hormones") in livestock production, in contrast to their legal use [e.g. of five such hormones (17beta-estradiol, testosterone, progesterone, trenbolone and zeranol) as small solid ear implants and two hormones as feed additives for feedlot heifers (melengestrol acetate) and for swine (ractopamine) in the USA], the regulatory controls also differ sharply between the EU and the USA.In the EU the treatment of slaughter animals is the regulatory offence that has to be controlled in inspection programs. In the USA testing for compliance of a regulatory maximum residue level in the edible product (muscle, fat, liver or kidney) is the purpose of the inspection program (if any).The EU inspection programs focus on sample materials that are more suitable for testing for banned substances, especially if the animals are still on the farm, such as urine and feces or hair. In the case of slaughtered animals, the more favored sample materials are bile, blood, eyes and sometimes liver. Only in rare occasions is muscle meat sampled. This happens only in the case of import controls or in monitoring programs of meat sampled in butcher shops or supermarkets.As a result, data on hormone concentrations in muscle meat samples from the EU market are very rare and are obtained in most cases from small programs on an ad hoc basis. EU data for natural hormones in meat are even rarer because of the absence of "legal natural levels" for these hormones in compliance testing. With the exception of samples from the application sites - in the EU the site of injection of liquid hormone preparations or the site of application of "pour on" preparations - the hormone concentrations observed in meat samples of illegally treated animals are typically in the range of a few micrograms per kilogram (ppb) down to a few tenths of a microgram per kilogram. In the EU dozens of illegal hormones are used and the number of active compounds is still expanding. Besides estrogenic, androgenic and progestagenic compounds also thyreostatic, corticosteroidal and beta-adrenergic compounds are used alone or in "smart" combinations.An overview is given of the compounds identified on the EU black market. An estimate is also given of the probability of consumption in the EU of "highly" contaminated meat from the application sites in cattle. Finally some data are presented on the concentration of estradiol in bovine meat from animals treated and not treated with hormone implants. These data are compared with the recent findings for estradiol concentrations in hen's eggs. From this comparison, the preliminary conclusion is that hen's eggs are the major source of 17alpha- and 17beta-estradiol in the consumer's daily "normal" diet.

Tetrahydrogestrinone analysis and designer steroids revisited

Anabolic steroids are the main abused class of prohibited substances in doping control. These steroids are associated with enhancement of muscular mass and aggressiveness, resulting in increased performance. Chromatography and MS have a key role among methods developed to detect anabolic steroids in doping control laboratories. However, the classical analytical approach fails in detection of the so-called ‘designer steroids’. This review focuses on the rise of tetrahydrogestrinone, a drug that became synonymous with designer steroids. The reasons why classical methods fail in tetrahydrogestrinone detection are discussed and how the detection was implemented is shown. Alternative strategies for detection of new drugs designed to cheat current analytical methodology are highlighted. Concern for the abuse of veterinary designer drugs and supplements is also acknowledged.

Bioactivity-based screening of antibiotics and hormones

Bioactivity-based screening methods are relatively cheap, quick and easy to use tools. Especially with respect to antimicrobial residues and compounds with hormonal activity, they form a very cost-effective alternative to physical chemical methods in large-scale surveillance and monitoring programs, where their main purpose is to identify samples that require additional chemical confirmation. A major advantage is their intrinsic capability to detect unknown compounds and new hazards. This review shows an overview of the available methods and their potential and limitations for regulatory control.

Identification of a probable new adrenergic agonist by nuclear magnetic resonance and mass spectrometry

In animal production, it is consolidated the synthesis and the illegal use of growth promoters of new generation, able to skip routine screening and confirmatory analysis. In this work it is reported the nuclear magnetic resonance (NMR) and the mass spectrometry identification of a probable new adrenergic drug found in a feed premix. The substance was selectively purified on alpha 1 acid glycoprotein affinity columns; then its structure was first achieved by recording the 13C NMR spectrum that gave the total number of carbons of the molecule, successively sorted by DEPT experiments into quaternary, CH, CH2, and CH3 groups. However, the complete assignments of all resonances were derived from the bi-dimensional analysis and the crucial indications from the 1H-13C reverse experiments. Further characterisation was performed by atmospheric pressure chemical ionisation both in positive and negative ion mode, matching the molecular ion and the fragmentation pattern with those of most recently described new adrenergic agonists. After the loss of a ter-butylic group, the structure shows an internal symmetry along with the presence of Chlorine clusters. The proposed formula of the compound, the 8,8'-diamino-9,9'-dichloro-1-terbutyl-1,1',4,4-tetrahydro-5H,5'H-2,2'-bi-1-benzazepine-5,5'-dione, partially resembles that of Zilpaterol for the presence of a heterocyclic ring; Further work is in progress to characterise the structure-activity relationship.

Multi-detection of corticosteroids in sports doping and veterinary control using high-resolution liquid chromatography/time-of-flight mass spectrometry

A liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS) method was developed using the latest high-resolution LC column technology, the ultra performance liquid chromatography (UPLC), and electrospray ionization (ESI) in the positive ion mode. Gradient UPLC separation conditions were optimized for a group of 22 analytes comprising 17 glucocorticosteroids, specific designer steroids such as tetrahydrogestrinone (THG) and specific beta2-agonists such as formoterol. The UPLC/TOFMS separation obtained required 5.5 min only for all the substances tested. Even the critical pair of dexamethasone and betamethasone isomers was almost completely resolved. Thanks to the over 10,000 full-width at half maximum (FWHM) mass resolution and high mass accuracy features of TOFMS 50 mDa window accurate mass chromatograms could be reconstructed for the individual analytes. Sensitive screening in human and calf urine samples fortified at the glucocorticosteroids minimum required performance limit (MRPL) of 30 microg L(-1) (human urine, sports doping) and 2 microg L(-1) (calf urine, veterinary control) could be obtained. The potential of UPLC/TOFMS for confirmatory analysis was shown by determining the accurate mass of all compounds and fragment ions upon in-source collision-induced dissociation (CID) at different energies. The exact mass measurement errors for all glucocorticosteroids were found to be within 6 ppm. Considering veterinary control, limits of detection (LOD) and limits of quantification (LOQ) were determined for most of the analytes in calf urine and found to range from 0.1 to 3.3 and from 0.4 to 4.4 microg L(-1), respectively. The method can be easily extended with other banned substances of interest, as demonstrated by the addition of 21 beta2-agonists to the original analyte mixture in urine, without causing any interferences.

Screening and confirmation criteria for hormone residue analysis using liquid chromatography accurate mass time-of-flight, Fourier transform ion cyclotron resonance and orbitrap mass spectrometry techniques

An emerging trend is recognised in hormone and veterinary drug residue analysis from liquid chromatography tandem mass spectrometry (LC/MS/MS) based screening and confirmation towards accurate mass alternatives such as LC coupled with time-of-flight (TOF), Fourier transform ion cyclotron resonance (FTICR) or Fourier transform orbitrap (FT Orbitrap) MS. In this study, mass resolution and accuracy are discussed for LC/MS screening and confirmation of targeted analytes and for the identification of unknowns using the anabolic steroid stanozolol and the designer beta-agonist "Clenbuterol-R" as model substances. It is shown theoretically and experimentally that mass accuracy criteria without proper mass resolution criteria yield false compliant (false negative) results, both in MS screening and MS/MS confirmation of stanozolol. On the other hand, previous medium resolution accurate mass TOFMS/MS data of the designer beta-agonist were fully confirmed by high resolution FT Orbitrap MS(n) experiments. A discussion is initiated through a proposal for additional criteria for the use of accurate mass LC/MS technologies, to be implemented in Commission Decision 2002/657/EC.

Multiresidue analysis of beta-agonists in pork by coupling polymer monolith microextraction to electrospray quadrupole time-of-flight mass spectrometry

A novel method of polymer monolith microextraction (PMME) using poly(methacrylic acid-co-ethylene glycol dimethacrylate) monolith combined with electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QTOF MS) was developed for the rapid and sensitive determination of beta-agonists in pork samples. The conditions of PMME were optimized for the improvement of extraction efficiency and reduction of the matrix interferences from pork. Under the optimal condition, the eluate solution allowed direct analysis by mass spectrometry. In the positive ion mode and in the multiple reaction monitoring (MRM) mode, the limits of detection (LODs) for beta-agonists were found to be 0.08 ng/g (clenbuterol, CLB), 0.18 ng/g (salbutamol, SBTM) and 0.26 ng/g (terbutaline, TBTL) in pork, respectively, with good inter- and intra-day precisions (2-10% for CLB, 11-23% for SBTM and 4-16% for TBTL). The proposed PMME/ESI-QTOF MS method was successfully applied to the determination of beta-agonist residues in thirteen real samples, and the positive samples were confirmed according to the identification points (IPs) system defined by Commission Decision 2002/657/EC. To investigate the matrix effect, the proposed method was compared with PMME-HPLC/ESI-QTOF MS and the slight decrease in sensitivity of PMME/ESI-QTOF MS was ascribed to the inter-analyte ion suppression.

Screening for estrogen residues in calf urine: Comparison of a validated yeast estrogen bioassay and gas chromatography–tandem mass spectrometry

Within the European Union, the control for residues of illegal hormones in food-producing animals is based on urine analysis for a few target analytes using gas chromatography/mass spectrometry and/or liquid chromatography-tandem mass spectrometry. Recently, we developed a robust yeast bioassay screening tool for estrogens, which was validated as a qualitative screening method in accordance with EC decision 2002/657/EC. In this study, we present long-term performance data and a comparison of urine data obtained with this bioassay, and data from an established gas chromatography-tandem mass spectrometry (GC/MS/MS) confirmatory analysis method. More than 120 calf urine samples from a controlled reference experiment were analysed using both protocols. According to the GC/MS/MS method, only the natural estrogens 17alpha-estradiol and estrone were present in the non-compliant samples. The bioassay was less sensitive than GC/MS/MS for the relatively weak estrogenic compound 17alpha-estradiol, in accordance with expectations. Assuming that application of the mass spectrometric method is considered beyond reasonable doubt, the bioassay performed very well: only 5.6% of the calf urine samples found compliant in GC/MS/MS were screened false suspect in the bioassay screening method. The bioassay results of non-compliant urine samples under routine conditions were as predicted, taking into account the relative estrogenicity of the natural estrogens 17alpha-estradiol and estrone vs. 17beta-estradiol. Only one sample was screened false negative for 17alpha-estradiol and estrone. Application of this fast and simple estrogen bioassay in routine surveillance and control can significantly reduce GC/MS/MS sample workload and allow higher percentages of animals to be screened for potential hormone abuse.

Analytical strategies for residue analysis of veterinary drugs and growth-promoting agents in food-producing animals—a review

After a brief introduction into the field of veterinary drugs and growth-promoting agents, the most important EU regulations and directives for the inspection of food-producing animals and animal products regarding the residue control of these substances are presented and discussed. Main attention in the review is on the methods of analysis in use today for the most important classes of veterinary drugs and growth-promoting agents viz. anthelmintics, antibiotics, coccidiostats, hormones, beta-agonists and tranquillizers. Emphasis is given to the potential, and limitations, of state-of-the-art analytical procedures and their performance characteristics. The most obvious conclusion is that, today (reversed-phase) liquid chromatography combined with tandem mass spectrometric detection--either triple-quadrupole or ion-trap multi-stage--is the preferred technique in a large majority of all cases. In the field of sample treatment, the combined use of liquid extraction--i.e., liquid partitioning or liquid-liquid extraction--and liquid-solid extraction--primary on- or off-line solid-phase extraction--is most popular. Finally, while the analytical tools required to meet the demands typically formulated by governments and international organizations today, generally speaking are available, several problems still do exist. To quote three examples, problems are encountered in the area of simultaneously extracting and pre-treating groups of analytes with mutually widely different polarities, with regard to identification-point--based confirmation of analyte identity, and regarding quantification errors caused by ion-suppression effects. Improving the speed of analysis is another aspect that should, and will, receive dedicated interest in the near future.

Evaluation of MISPE for the multi-residue extraction of β-agonists from calves urine

Methods based on molecular recognition mechanisms for the clean-up of veterinary drugs and their residues, such as immuno-, receptor- and acceptor-affinity and molecularly imprinted polymers (MIPs), have been described as selective tools to improve the selectivity and the reliability of analytical results. In this work, we tested the extraction recovery performances of a MISPE column, designed for multi-residual clean-up of beta-agonists. For this purpose, 18 different samples of calf urine were spiked at 0.25, 0.50 and 1.00 ppb with pooled standard solutions of clenbuterol (Clen), tulobuterol (Tolu), isoxsuprine (Isox), brombuterol (Brom), mapenterol (Mape) and ractopamine (Racto) and analysed on two independent analytical sessions, on a LC-MS/MS ion trap detector. Averaged recoveries, constant for each molecule considered, were 64.6% for Racto, 63.0% for Salm, 59.9% for Form, 54.7% for Brom, 52.0% for Clen, 41.8% for Mape, 38.6% for Tolu and 34.5% for Isox, respectively. Reproducibility studies gave a CV < 11% at the 0.25 ppb level. The decision limit for the identification of the target drugs ranged from 0.01 ppb for mapenterol to 0.19 ppb for salmeterol, when considering one precursor, and two product ions as identification points. Such findings indicate that the choice of the appropriate molecule as template in the MIP preparation is the critical factor to guarantee a reliable analytical multi-residue approach for beta-agonists, despite the structural differences among molecules exploiting almost the same pharmacological effect.