LC-MS-MS to detect and identify four beta-agonists and quantify clenbuterol in liver

Integrated recombinant gene yeast bioassay and HPLC-MS analysis for detection of low-dose multi-component residue of hormone-like compounds in environment

Illegal addition of low-dose multi-component residue of hormone-like compounds have sprung up in human activities and production as a cunning strategy to escape from sanitation monitoring, sowing a horrible seed for accidents in food security. Hence, combined strategies with accuracy and efficiency are urgently needed to overcome current circumstance and practical hurdles. Herein, an integrated analysis that compromises recombinant gene yeast bioassay (V400E-YES) and high-performance liquid chromatography-mass spectrometry (HPLC-MS) determination was developed promptly with distinguishing advantage as optimized V400E-YES provides a sum of hormone-like compounds in sample, and subsequent HPLC-MS analysis can accurately quantify the concentration of compounds. In terms of V400E-YES, large-scale random mutagenesis was performed to obtain higher sensitivity hormone receptors. Excitingly, single mutation of estrogen receptor (ER) at V400E and amphimutation of androgen receptor (AR) at G581R/D831E conferred the highest detection sensitivity with a more than 10-fold increase. Subsequently, sensitive HPLC-MS methods for simultaneous detection of eleven estrogens and nine androgens, respectively, were well-constructed. Utilizing this integrated and validated methods, we successfully investigated the hormone residue in environmental samples from farms in Jiangsu, China. Collectively, with multiple estrogens and androgens residue are being widely detected in soil and sewage samples, the feasibility of this method is highlighted, as well as the increasing lurking peril of hormone-like substance residues in environment.

High resolution mass spectrometry-based detection and quantification of β-agonists at relevant trace levels in a variety of animal-based food matrices

β-agonists have been illegally used for growth promoting purposes in animal husbandry, leading to residue concentrations capable of inducing acute toxic reactions among consumers of animal-based food. There is not only a need for detecting β-agonist residues at low concentrations, but also to increase the number of compounds to be monitored. It was therefore the aim of this paper to develop a unified method capable of detecting a wide range of different β-agonists (20 analytes including some metabolites) in a variety of matrices (muscle, liver, plasma, milk and urine). The developed procedure permits the quick processing of samples with limited labour input and consumption of consumables. The method has been validated according to the Commission Decision 98/536/EC. Detection is based on ultrahigh-performance chromatography coupled to high-resolution mass spectrometry. Validation was performed on two different instruments (Orbitrap and time of flight). The obtained limit of quantification (0.05 to 0.5 μg/kg and the average recovery of 78% in the most complex matrix (liver) satisfies current regulatory requirements.

Selection and Application of ssDNA Aptamers against Clenbuterol Hydrochloride Based on ssDNA Library Immobilized SELEX

Clenbuterol hydrochloride (CLB) is often abused as additive feed for livestock to decrease adipose tissue deposition and to increase growth rate. It raises a potential risk to human health through the consumption of animal product. In this study, aptamers with higher affinity and specificity were screened through 16 selection rounds based on the ssDNA library immobilized systematic evolution of ligands by exponential enrichment (SELEX) technique. After cloning and sequencing, five aptamer candidates were picked out for affinity and specificity assays based on a graphene oxide (GO) adsorption method. The results showed that the aptamer CLB-2 binds specifically against CLB with a dissociation constant, K_d, value of 76.61 ± 12.70 nM. In addition, an aptamer-based fluorescence bioassay was established for CLB analysis. The correlation between the CLB concentration and fluorescent signal was found to be linear within the range of 0.10 to 50 ng/mL with a limit of detection of 0.07 ng/mL. It has been further applied for the determination of CLB in pork samples, showing its great potential for sensitive analysis in food safety control.

Molecularly imprinted polymers as the extracted sorbents of clenbuterol ahead of liquid chromatographic determination

A pre-treatment methodology for clenbuterol hydrochloride (CLEN) isolation and enrichment in a complex matrix environment was developed through exploiting molecularly imprinted polymers (MIPs). CLEN-imprinted polymers were synthesized by the combined use of ally-β-cyclodextrin (ally-β-CD) and methacrylic acid (MAA), allyl-β-CD and acrylonitrile (AN), and allyl-β-CD and methyl methacrylate (MMA) as the binary functional monomers. MAA-linked allyl-β-CD MIPs (M-MAA) were characterized by Fourier transform-infrared (FT-IR) spectroscopy and a scanning electron microscope (SEM). Based upon the results, M-MAA polymers generally proved to be an excellent selective extraction compared to its references: AN-linked allyl-β-CD MIPs (M-AN) and MMA-linked allyl-β-CD MIPs (M-MMA). M-MAA polymers were eventually chosen to run through a molecularly imprinted solid-phase extraction (MISPE) micro-column to enrich CLEN residues spiked in pig livers. A high recovery was achieved, ranging from 91.03% to 96.76% with relative standard deviation (RSD) ≤4.45%.

Development, validation and application to real samples of a multiresidue LC-MS/MS method for determination of β2 -agonists and anabolic steroids in bovine hair

β(2) -agonists are often abused in cattle breeding because of their effects on animal growth and meat properties. The use of β(2) -agonists as growth promoters is forbidden in the European Union (Council Directive 96/23/EC classifies them into group A of Annex I), due to their toxicity and carcinogenic properties, as for anabolic steroids, which are often administered in combination with β(2) -agonists, to promote the storage of proteins and increase muscle size. A unique confirmatory liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantitative detection of 13 β(2) -agonists and anabolic steroids plus the qualitative identification of other three analytes in bovine hair was developed and validated, according to Decision 2002/657/CE. Hair samples were washed with dichloromethane, digested within a NaOH solution and subjected to liquid-liquid extraction. The analysis was performed by high performance liquid chromatography coupled to a triple quadrupole mass spectrometer operating in the selected reaction monitoring mode. The absence of matrix interferents, together with good repeatability of both retention times and relative abundances of diagnostic transitions, allowed the correct identification of all analytes. The quantitative calibrations obtained from spiked blank hair samples proved linear in the range tested. CCα and CCβ ranged from 0.5 ng/g to 30 ng/g. Intralaboratory reproducibility (CV%) ranged between 5.0 and 17.7 and trueness between 96% ± 7% and 105% ± 8%. The applicability of the method to real positive samples was demonstrated for both β(2) -agonists and anabolic steroids. 17α-boldenone was found in most (70%) hair samples obtained from untreated animals, supporting the hypothesis of endogenous production of this steroid.

Challenges in implementing a screening method for veterinary drugs in milk using liquid chromatography quadrupole time-of-flight mass spectrometry

High resolution mass spectrometry (HRMS) is a valuable tool for the analysis of chemical contaminants in food. Our laboratory has successfully developed methods to screen for veterinary drug residues using liquid chromatography quadrupole time-of-flight (Q-TOF). There have been, however, significant challenges as methods are transferred from the development stage to routine regulatory analysis. Having experimental retention time and product ion information for analytes greatly facilitates the ability to determine if residues found by the HRMS searching software are false detects. These data were collected for over 200 veterinary drug residues using LC Q-TOF MS. The screening levels of detection for over 150 veterinary drug residues in milk were determined, and over half of those tested can be detected at concentrations of 10 ng/mL or less; 72% can be found in milk when present at 100 ng/mL. Tentative identification of the product ions from these analytes is also presented.

Simultaneous detection of residues of 25 β₂-agonists and 23 β-blockers in animal foods by high-performance liquid chromatography coupled with linear ion trap mass spectrometry

A sensitive method has been developed for the simultaneous determination of residues of 25 β₂-agonists and 23 β-blockers in animal foods by high-performance liquid chromatography coupled with linear ion trap mass spectrometry (HPLC-LIT-MS). This method is based on a new procedure of hydrolysis and extraction by 5% trichloracetic acid, and then cleaned up by mixed strong cation exchange (MCX) cartridges coupled with a novelty cleanup step by methanol. Methanol and 0.1% formic acid were used as mobile phases for gradient elution, while a Supelco Ascentis Express Rp-Amide column was used for LC separation. ESI positive ion scan mode was used with consecutive reaction monitoring (CRM, MS³). Nine β₂-agonists labeled by the deuterium isotope were used as internal standards for quantification. The linear ranges of 48 analytes were from 5 to 200 μg/L; the coefficient of correlation was not less than 0.995. Blank pork muscle, blank liver, and blank kidney were selected as representative matrix for spiked standard recovery test. The recoveries of each compound were in the range of 46.6-118.9%, and the relative standard deviations were in the range of 1.9-28.2%. Decision limits (CCα, α = 0.01) of 48 analytes in muscles, liver, and kidney samples ranged from 0.05 to 0.49 μg/kg, and the detection capability (CCβ, β = 0.05) ranged from 0.13 to 1.64 μg/kg. This method was successfully applied to 110 real animal origin food samples including meat, liver, and kidney of pig and chicken samples.

Flow injection chemiluminescent determination of clenbuterol using GoldMag particles as carrier

A novel flow injection chemiluminescent (CL) enzyme immunoassay for clenbuterol analysis based on GoldMag particles is described. GoldMag is a new type of super-paramagnetic Fe3O4/Au composite particle used as a carrier in a flow injection CL system. Clenbuterol conjugated with ovalbumin (OVA) was immobilized onto GoldMag particles and the particles fixed in a micro-channel by an external electromagnetic field. The clenbuterol test sample and clenbuterol polyclonal antibody (Ab) were injected into the channel and incubated with GoldMag particles. Clenbuterol, immobilized on the magnetic particle surfaces, competes for polyclonal antibodies with clenbuterol in the test sample. The free Ab or Ab combined with the clenbuterol sample was washed away and the magnetic particles conjugated with Ag-Ab left in the micro-channel. Horseradish peroxidase (HRP)-labelled goat anti-rabbit immunoglobulin G (IgG) was added and reacted with clenbuterol polyclonal antibodies; excess goat anti-rabbit-HRP was then washed off. When chemiluminescent reagents were injected into the channel, emitted light from the magnetic particle surface was measured and recorded using a photomultiplier-based apparatus. The linear range of this novel method was 0.01-0.1 ng g(-1) and recovery of clenbuterol was 85-105% with a RSD of 3.2% (n = 11).

Extraction and preconcentration of salbutamol and terbutaline from aqueous samples using hollow fiber supported liquid membrane containing anionic carrier

This paper presents a new three-phase liquid-phase microextraction (LPME) strategy for extraction and preconcentration of salbutamol (SB) and terbutaline (TB) from aqueous samples, including urine. The drugs were extracted from 11 ml of aqueous sample (source phase; SP) into an organic phase with microliter volume located inside the pores of a polypropylene hollow fiber, and then back-extracted into 24 microl of a second aqueous solution as the receiving phase (RP), located in the lumen of the hollow fiber. In preliminary experiments, we tried to transport the drugs using a pH gradient between the two sides of the hollow fiber. Due to the existence of both amine and phenolic groups on the drugs, very little transport occurred and enrichment factors (EF) less than one were obtained. Further experiments were done in the presence of bis(2-ethylhexyl) monohydrogenphosphoric acid (D2EHPA) or methyltrioctylammonium chloride (Aliquat 336) in the organic phase, to extract drugs from acidic and basic matrices, respectively. Results showed that transport of drugs from alkaline solution into 1M of sodium bromide occurred when the membrane was impregnated with dihexyl ether containing 20% Aliquat 336. To optimize the EF, the effects of different parameters such as the nature of organic solvent used to impregnate the membrane, compositions and volumes of SP and RP, type and concentration of carrier, extraction time and stirring rate were investigated. Optimal results were obtained in the presence of 0.005 M of NaOH (pH 11.70) in the SP, 1M of NaBr in the RP, 20% of Aliquat 336 in dihexyl ether as membrane impregnation solvent, stirring rate of 500 rpm and extraction time of 60 min. Under these conditions, enrichment factors of 52.9 and 213.1, dynamic linear ranges of 20-5000 and 10-5000, and limits of detection of 2.5 and 0.5 ng/ml were obtained for salbutamol and terbutaline, respectively. Also determination of drugs in environmental water and urine samples in the range of nanograms per millilitre with RSDs<10% was possible using HPLC-photodiode array detection or HPLC-MS.

Determination of β2-agonists by ion chromatography with direct conductivity detection

A simple method for the simultaneous detection of four beta2-agonists (salbutamol, fenoterol, clorprenaline, and clenbuterol) using ion chromatography (IC) with direct conductivity detection (CD) based on their ionization in acidic medium without chemical suppression is presented. The mixture of 1.8 mM HNO3 and 2% (v/v) acetonitrile was used as eluent. The method could be applied to the determination of the beta2-agonists in pharmaceutical preparations. The recovery of salbutamol and clenbuterol in tablets was more than 97% (n=3) and the relative standard deviation (n=11) less than 2.8%. With the proposed method, salbutamol could also be successfully detected in human plasma. In a single chromatographic run, the four beta2-agonists can be separated and determined in less than 8 min. The linear ranges were of 7.0-1.4 x 10(3)ng/ml for salbutamol, 34-7.8 x 10(3)ng/ml for fenoterol, 8.0-1.6 x 10(3)ng/ml for clorprenaline, and 25-7.5 x 10(3)ng/ml for clenbuterol. The detection limits were 2.0 ng/ml for salbutamol, 10 ng/ml for fenoterol, 3.0 ng/ml for clorprenaline, and 10 ng/ml for clenbuterol.

Liquid chromatography/electrospray ionization tandem mass spectrometric screening and confirmation methods for beta2-agonists in human or equine urine

Electrospray ionization (ESI) mass spectra of 19 common beta(2)-agonists were investigated in terms of fragmentation pattern and dissociation behavior of the analytes, proving the origin of fragment ions and indicating mechanisms of charge-driven and charge-remote fragmentation. Based on these data, liquid chromatographic/ESI tandem mass spectrometric (LC/ESI-MS/MS) screening and confirmation methods were developed for doping control purposes. These procedures employ established sample preparation steps including either acidic or enzymatic hydrolysis, alkaline extraction and, in the case of equine urine specimens, acidic re-extraction of the analytes. In addition, a degradation product of formoterol caused by acidic hydrolysis during sample preparation could be identified and utilized as target compound in screening and also confirmation methods. The screening procedures cover 18 or 19beta(2)-agonists, the estimated limits of detection of which for equine and human urine samples vary between 2 and 100 ng ml(-1) and between 2 and 50 ng ml(-1), respectively. A single LC/MS/MS analysis can be performed in 9 min.

Progress of liquid chromatography-mass spectrometry in clinical and forensic toxicology

The use of liquid chromatography-mass spectrometry (LC-MS) has recently exploded in various analytic fields, including toxicology and therapeutic drug monitoring (although still far behind pharmacokinetics). There is no doubt that LC-MS is currently competing with gas chromatography (GC)-MS for the status of the reference analytic technique in toxicology. This review presents, for the nonspecialist reader, the principles, advantages, and drawbacks of LC-MS systems using atmospheric pressure interfaces. It also gives an overview of the analytic methods for xenobiotics that could be set up with these instruments for clinical or forensic toxicology. In particular, as far as quantitative techniques are concerned, this review tries to underline the large number and variety of drugs or classes of drugs (drugs of abuse, therapeutic drugs) or toxic compounds (e.g., pesticides) that can be readily determined using such instruments, the respective merits of the different ionization sources, and the improvements brought about by tandem MS. It also discusses new applications of LC-MS in the field of toxicology, such as "general unknown" screening procedures and mass spectral libraries using LC-atmospheric pressure ionization (API)-MS or MS-MS, presenting the different solutions proposed to overcome the naturally low fragmentation power of API sources. Finally, the opportunities afforded by the most recent or proposed instrument designs are addressed.

Quantification of clenbuterol in equine plasma, urine and tissue by liquid chromatography coupled on-line with quadrupole time-of-flight mass spectrometry

Clenbuterol (CBL) is a potent beta(2)-adrenoceptor agonist used for the management of respiratory disorders in the horse. The detection and quantification of CBL can pose a problem due to its potency, the relatively low dose administered to the horse, its slow clearance and low plasma concentrations. Thus, a sensitive method for the quantification and confirmation of CBL in racehorses is required to study its distribution and elimination. A sensitive and fast method was developed for quantification and confirmation of the presence of CBL in equine plasma, urine and tissue samples. The method involved liquid-liquid extraction (LLE), separation by liquid chromatography (LC) on a short cyano column, and pseudo multiple reaction monitoring (pseudo-MRM) by electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS). At very low concentrations (picograms of CBL/mL), LLE produced better extraction efficiency and calibration curves than solid-phase extraction (SPE). The operating parameters for electrospray QTOF and yield of the product ion in MRM were optimized to enhance sensitivity for the detection and quantification of CBL. The quantification range of the method was 0.013-10 ng of CBL/mL plasma, 0.05-20 ng/0.1 mL of urine, and 0.025-10 ng/g tissue. The detection limit of the method was 13 pg/mL of plasma, 50 pg/0.1 mL of urine, and 25 pg/g of tissue. The method was successfully applied to the analysis of CBL in plasma, urine and various tissue samples, and in pharmacokinetic (PK) studies of CBL in the horse. CBL was quantified for 96 h in plasma and 288 h in urine post-administration of CLB (1.6 micro g/kg, 2 x daily x 7 days). This method is useful for the detection and quantification of very low concentrations of CBL in urine, plasma and tissue samples.

Quantitative detection of salmeterol after inhalation in equine urine by liquid chromatography/tandem mass spectrometry

A sensitive, accurate and precise liquid chromatography/tandem mass spectrometry (LC/MS(2)) method was developed for the quantification of salmeterol in the urine of horses. The method consists of a liquid-liquid extraction with tert-butylmethyl ether and isopropanol at pH 12 after enzymatic hydrolysis. The extracts are analysed using an LC/MS system equipped with an electrospray ionisation (ESI) probe. Method validation showed excellent linearity, specificity, accuracy, precision and intra-laboratory repeatability and reproducibility. The limit of quantitative detection was 0.25 ng/mL and the limit of detection was 0.125 ng/mL. The excretion profile was determined after administration of 500 microg salmeterol (Serevent) to four standard-bred mares via a metered dose inhaler (MDI) with an Equinehaler adapter. Salmeterol was detected from 1 h until 12 h post-administration. Maximum urinary concentrations varied between 2.3 and 14.9 ng/mL.

Clenbuterol ingestion causing prolonged tachycardia, hypokalemia, and hypophosphatemia with confirmation by quantitative levels

BACKGROUND

Clenbuterol is a long acting beta2-adrenergic agonist used in the treatment of pulmonary disorders. Acute clenbuterol toxicity resembles that of other beta2-adrenergic agonists. Most previously reported cases of clenbuterol toxicity describe patients who ate livestock illicitly treated with clenbuterol.

CASE REPORT

We report a case of human clenbuterol toxicity confirmed and correlated with qualitative and quantitative serum clenbuterol assays. This poisoned patient, a 28-year-old woman, developed sustained sinus tachycardia at 140/min, hypokalemia (2.4 mEq/L, 2.4 mmol/L), hypophosphatemia (0.9 mg/dL, 0.29 mmol/L), and hypomagnesemia (1.52 mg/dL, 0.76 mmol/L) after ingesting a reportedly small quantity of clenbuterol. The patient received repeated doses of metoprolol to treat her cardiovascular stimulation and potassium chloride to treat her hypokalemia. She remained symptomatic for more than 20 hours after the ingestion. Analysis by enzyme-linked immunosorbent assay and liquid chromatography/mass spectrometry revealed a serum clenbuterol concentration of 2.93 mcg/L 3 hours after the ingestion and an undetectable serum concentration 20 hours after ingestion. It is noteworthy that at a serum concentration below the limit of detection by liquid chromatography/mass spectrometry, the patient remained symptomatic. Acute clenbuterol toxicity is rarely reported following illicit use in humans, and this is the first such case to provide confirmatory toxicological analysis.

Evaluation of commercial immunoassays for cross-reactivity to clenbuterol stereoisomers and bovine metabolites

Several commercially available immunoassay kits have been developed to detect the beta-adrenergic agonist clenbuterol HCl. Technical materials supplied with the kits do not generally report cross-reactivity with clenbuterol metabolites. Use of such kits to quantitate clenbuterol might lead to an overestimation of parent drug if metabolites were present. The objective of this study was to measure the cross-reactivity of clenbuterol metabolites with several commercially available clenbuterol immunoassays. Three clenbuterol-glucuronide conjugates, clenbuterol-sulphamate, 4-amino-3,5-dichloro-hippuric acid (clenbuterol-hippurate), and purified clenbuterol-stereoisomers were tested for cross-reactivity. The clenbuterol-sulphamate metabolite showed significant cross-reactivity (42-77%), but clenbuterol-hippurate showed very little competition (< 0.2%) towards clenbuterol. Clenbuterol-glucuronides had little (0.1-1.6%) cross-reactivity. In addition, (R)-, (S)-, and racemic clenbuterol were used to determine the stereospecificity of the kits. Both (R)- and (S)-clenbuterol competed for binding in two of the kits, however, in one kit the (S)-clenbuterol stereoisomer had an affinity 100 times greater than the (R)-stereoisomer. The presence of significant quantities of the sulphamate metabolite of clenbuterol in a biological matrix would cause an overestimation of the amount of parent clenbuterol. This study illustrates the inherent problems of using unvalidated immunoassays for quantitation purposes.

Beta2-agonist extraction procedures for chromatographic analysis

Normally, different procedures were necessary to prepare sample matrices for chromatographic determination of beta2-agonists. The present review includes sampling, pre-treatment and extraction/purification for urine, plasma, liver, meat, feeds, hair and milk powder, as previous steps for chromatographic analysis of beta2-agonists. Six methodologies were especially revised for extraction/purification namely, liquid-liquid extraction, solid-phase extraction (SPE), matrix solid-phase dispersion, immunoaffinity chromatography, dialysis and supercritical fluid extraction. SPE was discussed in detail and five mechanisms were described: adsorption, apolar, polar, ion-exchange and mixed phase. A brief conclusion in this field was also outlined.