Simultaneous determination of eight β-adrenergic agonists in human urine by an isotope dilution-online clean-up system coupled with liquid chromatography-tandem mass spectrometry

β-Adrenergic agonist compounds are medicines that open up the lung's medium and large airways. β-Adrenergic agonist compounds have been illegally or legally used to increase lean muscle mass in meat animals, bodybuilding, weight-loss programs, and athletes. Developing a rapid analytical approach for determining β-adrenergic agonist compounds in biological samples is crucial for individual exposure assessment. This study established an analytical method for simultaneously measuring eight β-adrenergic agonist compounds in human urine, including clenbuterol, terbutaline, salbutamol, ractopamine, zilpaterol, cimaterol, tulobuterol, and fenoterol. Two hundred microliters of a urine sample were added to eight deuterium-labeled internal standard mixtures and glucuronidase/arylsulfatase for enzymatic hydrolysis, and were then analyzed using an online clean-up system coupled with a liquid chromatography-tandem mass spectrometry system (LC-MS/MS). The limit of quantification ranged from 0.03 to 0.12 ng/mL urine for the eight β-adrenergic agonist compounds. The relative standard deviations (RSD) of the within-run and between-run precisions were less than 10%, and the relative accuracy errors were less than 17% in the three-level spiked artificial urine samples. Two hundred eighty human urine samples collected from the general population in Taiwan were assessed to demonstrate the capability and feasibility of this method. The detection frequencies were 33% for clenbuterol, 5% for ractopamine, and less than 5% for the others. We concluded that the isotope dilution-online clean-up system coupled with LC-MS/MS method is a valuable analytical method for investigating urinary β-adrenergic agonist compounds in humans and is valuable for human biomonitoring studies.

Undeclared Doping Substances are Highly Prevalent in Commercial Sports Nutrition Supplements

Sports nutrition supplements have previously been reported to contain undeclared doping substances. The use of such supplements can lead to general health risks and may give rise to unintentional doping violations in elite sports. To assess the prevalence of doping substances in a range of high-risk sports nutrition supplements available from Dutch web shops. A total of 66 sports nutrition supplements - identified as potentially high-risk products claiming to modulate hormone regulation, stimulate muscle mass gain, increase fat loss, and/or boost energy - were selected from 21 different brands and purchased from 17 web shops. All products were analyzed for doping substances by the UK life sciences testing company LGC, formerly known as the Laboratory of the Government Chemist, using an extended version of their ISO17025 accredited nutritional supplement screen. A total of 25 out of the 66 products (38%) contained undeclared doping substances, which included high levels of the stimulants oxilofrine, β-methylphenethylamine (BMPEA) and N,β-dimethylphenethylamine (NBDMPEA), the stimulant 4-methylhexan-2-amine (methylhexaneamine, 1,3-dimethylamylamine, DMAA), the anabolic steroids boldione (1,4-androstadiene-3,17-dione) and 5-androstene-3β,17α-diol (17α-AED), the beta-2 agonist higenamine and the beta-blocker bisoprolol. Based upon the recommended dose and the potential variability of analyte concentration, the ingestion of some products identified within this study could pose a significant risk of unintentional doping violations. In addition to inadvertent doping risks, the prescribed use of 3 products (4.5%) could likely impose general health risks.

Facile synthesis of magnetic sulfonated covalent organic framework composites for simultaneous dispersive solid-phase extraction and determination of β-agonists and fluoroquinolones in food samples

In this work, an efficient method for the determination of β-agonists and fluoroquinolones was established, based on a mixed-mode sorbent of magnetic sulfonated covalent organic framework composites. By coupling with HPLC-MS/MS, the main factors that affect the extraction procedure were optimized. Under the optimal conditions, the proposed HPLC-MS/MS method was successfully utilized for the extraction of β-agonists and fluoroquinolones in milk and pork meat samples. The method showed good linearities (R² ≥ 0.9916), and low LOQs of 0.1-0.2 ng g^-1 for β-agonists and fluoroquinolones. The adsorption mechanism was investigated with the assistance of quantum chemistry calculation method, and it is worth noting that the sorbent relied mainly on the multiple adsorption mechanisms, including π-π stacking, hydrophobic, electrostatic attraction and hydrogen-bonding interactions. This work not only provides a simple method for the preparation of a mixed-mode sorbent, but also a routine analysis strategy for monitoring the illegal use of β-agonists and fluoroquinolones.

A molecularly imprinted electrochemiluminescence nanoprobe based on complexes consisting of CdTe and multiwall carbon nanotube for sensitive determination of clenbuterol

An electrochemiluminescence (ECL) nanoprobe was fabricated for the determination of clenbuterol (CLB). A molecularly imprinted polymer (MIP) film was coated on the surface of the glassy carbon electrode modified with CdTe-doped multiwall carbon nanotubes. The MIP film with CLB as the template molecule improves the selectivity of the nanoprobe, CdTe is used as ECL signal amplifier, and MWCNT works as the carrier. The ECL intensity is altered by elution and reabsorption of CLB. The possible reaction mechanism and experimental parameters of the nanoprobe are discussed. Under optimized conditions, the quenched ECL intensity and the CLB concentration have a linear relationship in the range 2.3 × 10^-9 to 1.5 × 10^-5 mol·L^-1, and the detection limit is 1.0 × 10^-9 mol·L^-1 (S/N = 3). The nanoprobe was successfully applied to the determination of CLB in pork samples. Graphical abstract Schematic representation of the molecularly imprinted electrochemiluminescence nanoprobe based on complexes consisting of CdTe and multiwall carbon nanotube used to determinate clenbuterol.

A novel microfluidic paper-based analytical device based on chemiluminescence for the determination of β-agonists in swine hair

β-Agonists are illegal feed additives in the feed industries of many countries, especially China. Here, we report a microfluidic paper-based analytical device (μPAD) coupled with the chemiluminescence (CL) method to provide the sensitive, simple and rapid quantitative detection of β-agonists in swine hair samples. In this study, we found that the β-agonists diminished the CL generated by the reaction of K3[Fe(CN)6] and luminol on μPAD, which was different from that observed in the aqueous solution, and the degree of diminishment was proportional to the concentration of β-agonists. The possible mechanism was discussed as well. Also, this detection method showed a wide linear range (from 4.0 × 10-8 to 1.0 × 10-5 mol L-1) and low limit of detection (2.0 × 10-8 mol L-1) with a low consumption of samples and reagents. Satisfactory recovery values (from 78% to 95%) were achieved. Therefore, our μPAD CL sensor will be favorable to develop a miniaturized instrument for the on-site analysis of β-agonists in swine hair samples.

Determination of ractopamine and salbutamol in pig hair by liquid chromatography tandem mass spectrometry

A liquid chromatography tandem mass spectrometric method was developed for the determination of two β-agonists (ractopamine and salbutamol) in pig hair samples. An isotope of ractopamine-d5 or salbutamol-d6 as an internal standard was used to carry out quantitative analysis. Concentrated sodium hydroxide was used to pretreat hair samples and then purified by the solid phase extraction (SPE) procedure. The extracted solution was evaporated and reconstituted for injection in the instrument with electrospray ionization (ESI) operating in a positive multiple-reaction-monitoring (MRM) mode. Ractopamine and salbutamol separation were performed on C18 analytical column under gradient condition. The internal standard calibration curve was linear in the range of concentration from 0.5 to 100 ng mL⁻¹ (R² > 0.995). Recoveries of this method estimated at three spiked concentrations of 100, 250 and 500 ng mL⁻¹ in pig hair samples, were 79–82% for ractopamine and 77–96% for salbutamol. The corresponding inter-day and intra-day precisions expressed as relative standard deviation (RSD %) were 3.8–6.4% and 3.8–8.6%, respectively. The analytical time for one sample was 8 min. The detection limit of this method was 0.6 and 8.3 ng mL⁻¹ for ractopamine and salbutamol, respectively. This developed method can be applied for monitoring the use of the β-agonists salbutamol and ractopamine in swine feed incurred pig hair.

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.

Development of a highly sensitive and specific monoclonal antibody based enzyme-linked immunosorbent assay for the detection of a new β-agonist, phenylethanolamine A, in food samples

BACKGROUND

All β-agonists are banned as feed additives for growth promotion in animals due to toxic effects on humans after consuming the β-agonist contaminated meats. Phenylethanolamine A (PA) is a newly emerged β-agonist. Thus there is a need to develop highly sensitive and specific analytical methods for the detection of PA in food samples. In this study, the monoclonal antibody (mAb) against PA was produced by hybridoma technology and used for the development of enzyme-linked immunosorbent assay (ELISA).

RESULTS

The IC₅₀ values and limits of detection (LODs) of the ELISA using homogeneous combination of coating antigen/antibody for PA were 0.16 ng mL^-1 and 0.011 ng mL^-1 , respectively. The cross-reactive (CR) values of the assay with 14 structurally related β-agonists were lower than 0.59%. Swine liver and meat samples were spiked with PA at different content and analysed by ELISA. Acceptable recovery rates of 91.40-105.51% and intra-assay coefficients of variation of 1.56-9.92% (n = 3) were obtained. The ELISA for seven spiked samples was confirmed by LC-MS/MS with a high correlation coefficient of 0.9881.

CONCLUSION

The proposed mAb-based ELISA was highly sensitive and specific for PA and could be used as a quantitative/screening method for PA analysis in food samples. © 2016 Society of Chemical Industry.

Beta-agonist residues in cattle, chicken and swine livers at the wet market and the environmental impacts of wastewater from livestock farms in Selangor State, Malaysia

Fourteen beta-agonists were quantitatively analyzed in cattle, chicken and swine liver specimens purchased at 14 wet markets in Selangor State, Malaysia, by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The health risks of ractopamine and clenbuterol residues in the Malaysian population were assessed based on quantitative data and meat consumption statistics in Malaysia. Wastewater samples collected at swine farms (n = 2) and cattle/cow farms (n = 2) in the Kuala Langat district were analyzed for the presence for the 14 compounds. Wastewater in chicken farms was not collected because there was negligible discharge during the breeding period. The environmental impacts caused by beta-agonists discharged from livestock farms were spatially assessed in the Langat River basin using a geographic information system (GIS). As a result, 10 compounds were detected in the liver specimens. Ractopamine, which is a permitted compound for swine in Malaysia, was frequently detected in swine livers; also, 9 other compounds that are prohibited compounds could be illegally abused among livestock farms. The health risks of ractopamine and clenbuterol were assessed to be minimal as their hazard quotients were no more than 7.82 × 10^-4 and 2.71 × 10^-3, respectively. Five beta-agonists were detected in the wastewater samples, and ractopamine in the swine farm resulted in the highest contamination (30.1 μg/L). The environmental impacts of the beta-agonists in the Langat River basin were generally concluded to be minimal, but the ractopamine contamination released from swine farms was localized in coastal areas near the estuary of the Langat River basin because most swine farms were located in that region.

Exposure assessment of chemical hazards in pork meat, liver, and kidney, and health impact implication in Hung Yen and Nghe An provinces, Vietnam

OBJECTIVES

This study assesses the risk of exposure to hazardous chemical residues in pork meat, liver, and kidney collected at wet markets in Nghe An and Hung Yen provinces and discusses health impact implication.

METHODS

514 pig feed, kidney, liver, and pork samples were pooled and qualitatively and quantitatively analyzed for tetracyclines, fluoroquinolones, sulphonamide, chloramphenicol, β-agonists, and heavy metals. We compare the results with current regulations on chemical residues and discuss health implications.

RESULTS

Legal antibiotics were found in feed. Tetracycline and fluoroquinolones were not present in pork, but 11% samples were positive with sulfamethazine above maximum residue limits (MRL); 11% of packaged feed and 4% of pork pooled samples were positive for chloramphenicol, a banned substance; two feed, two liver, and one pork samples were positive for β-agonists but did not exceed current MRL; 28% of pooled samples had lead, but all were below MRL; and all samples were negative for cadmium and arsenic. Thus, the health risks due to chemical hazards in pork in Hung Yen and Nghe An seemed not as serious as what were recently communicated to the public on the mass media.

CONCLUSIONS

There is potential exposure to sulphonamide, chloramphenicol, and β-agonists from pork. Risk communication needs to focus on banned chemicals, while informing the public about the minimal risks associated with heavy metals.

Spatial analysis and source profiling of beta-agonists and sulfonamides in Langat River basin, Malaysia

Beta-agonists and sulfonamides are widely used for treating both humans and livestock for bronchial and cardiac problems, infectious disease and even as growth promoters. There are concerns about their potential environmental impacts, such as producing drug resistance in bacteria. This study focused on their spatial distribution in surface water and the identification of pollution sources in the Langat River basin, which is one of the most urbanized watersheds in Malaysia. Fourteen beta-agonists and 12 sulfonamides were quantitatively analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A geographic information system (GIS) was used to visualize catchment areas of the sampling points, and source profiling was conducted to identify the pollution sources based on a correlation between a daily pollutant load of the detected contaminant and an estimated density of human or livestock population in the catchment areas. As a result, 6 compounds (salbutamol, sulfadiazine, sulfapyridine, sulfamethazine, sulfadimethoxine and sulfamethoxazole) were widely detected in mid catchment areas towards estuary. The source profiling indicated that the pollution sources of salbutamol and sulfamethoxazole were from sewage, while sulfadiazine was from effluents of cattle, goat and sheep farms. Thus, this combination method of quantitative and spatial analysis clarified the spatial distribution of these drugs and assisted for identifying the pollution sources.

Seasonal occurrence of antibiotics and a beta agonist in an agriculturally-intensive watershed

We evaluated the occurrence of 12 veterinary antibiotics and a beta agonist over spatial and temporal scales in Shell Creek, an intensively agricultural watershed in Nebraska, using Polar Organic Chemical Integrative Samplers (POCIS). Twelve pharmaceuticals were detected with concentrations ranging from 0.0003 ng/L to 68 ng/L. The antibiotics measured at the highest time-weighted average concentrations were lincomycin (68 ng/L) and monensin (49 ng/L), and both compounds were detected at increased concentrations in summer months. Analysis of variance indicates that mean concentrations of detected pharmaceuticals have no significant (p > 0.01) spatial variation. However, significant temporal differences (p < 0.01) were observed. This study demonstrates the utility of passive samplers such as POCIS for monitoring ambient levels of pharmaceuticals in surface waters.

Rapid and sensitive determination of clenbuterol in porcine muscle and swine urine using a fluorescent probe

The feed additive Clenbuterol hydrochloric acid (CLB) is non-fluorescent, thus it is difficult to quantify through direct fluorescent method. Palmatine (PAL) can react with cucurbit[7]uril (CB[7]) to form stable complexes as a fluorescent probe. Significant quenching of the fluorescence intensity of the CB[7]-PAL complex was observed with the addition of CLB. Based on the significant quenching of the supramolecular complex fluorescence intensity, a novel spectrofluorimetric method with high convenience, selectivity and sensitivity was developed for the determination of CLB. The fluorescence quenching values (ΔF) showed good linear relationship with CLB concentrations from 0.011 μg mL(-1) to 4.2 μg mL(-1) with a detection limit 0.004 μg mL(-1). In this research, an ultrasound treatment replaced the former time-consuming shake method to form stable complexes. The proposed spectrofluorimetric method had been successfully applied to the determination of CLB in porcine muscle and swine urine with good precision and accuracy. The competing reaction and the supramolecular interaction mechanisms between the CLB and PAL as they fight for occupancy of the CB[7] cavity were studied using spectrofluorimetry, (1)H NMR, and molecular modeling calculations. Interestingly, results indicate that two stable CB[7]-CLB complexes were formed.

Ultratrace LC-MS/MS analysis of segmented calf hair for retrospective assessment of time of clenbuterol administration in Agriforensics

In agriforensics, time of administration is often debated when illegal drug residues, such as clenbuterol, are found in frequently traded cattle. In this proof-of-concept work, the feasibility of obtaining retrospective timeline information from segmented calf tail hair analyses has been studied. First, an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) hair analysis method was adapted to accommodate smaller sample sizes and in-house validated. Then, longitudinal 1 cm segments of calf tail hair were analyzed to obtain clenbuterol concentration profiles. The profiles found were in good agreement with calculated, theoretical positions of the clenbuterol residues along the hair. Following assessment of the average growth rate of calf tail hair, time of clenbuterol administration could be retrospectively determined from segmented hair analysis data. The data from the initial animal treatment study (n = 2) suggest that time of treatment can be retrospectively estimated with an error of 3-17 days.

Ultrasensitive and quantitative detection of a new β-agonist phenylethanolamine A by a novel immunochromatographic assay based on surface-enhanced Raman scattering (SERS)

Phenylethanolamine A (PA) is a new kind of β-agonist, which was illegally used as a feed additive for growth promotion in China. In this study, a novel immunochromatographic assay (ICA) based on surface-enhanced Raman scattering (SERS) for the ultrasensitive and quantitative detection of phenylethanolamine A is presented. The principle of this new ICA is similar to that based on colloidal gold particles, but using Au(MBA)@Ag-Ab [e.g., polyclonal antibody of PA labeled Au@Ag core-shell nanoparticles (NPs) sandwiched with a Raman reporter (4-mercaptobenzoic acid, MBA)] as a probe. After ICA procedures, the specific Raman scattering intensity of MBA on the test line was measured for quantitative detection of PA. This assay was completed within 15 min. The IC50 and limit of detection (LOD) values of the ICA for PA detection were 0.06 ng mL(-1) and 0.32 pg mL(-1), respectively, which were 1-3 orders of magnitude lower than those obtained by other immunoassays, indicating the ultrasensitivity of this ICA. There was no cross-reactivity (CR) of the assay with another three β-agonists (ractopamine, clenbuterol, and salbutamol), suggesting high specificity of the SERS-based ICA. A spiking experiment revealed that the recoveries of PA from pig urine samples were in range of 99.9- 101.2% with relative standard deviations (RSDs) of 3.6-5.8%. The results demonstrated that this SERS-based ICA was able to quantitatively detect PA in urine samples with high sensitivity, specificity, precision, and accuracy and might be a powerful method for the analysis of other target analytes in the food area.

Determination of the enrichment of isotopically labelled molecules by mass spectrometry

A general method for the determination of the enrichment of isotopically labelled molecules by mass spectrometry (MS) is described. In contrast to other published procedures, the method described here takes into account and corrects for measurement errors such as the contribution at M - 1 due to loss of hydrogen or lack of spectral resolution and provides an uncertainty value for the determined enrichment. The general procedure requires the following steps: (1) evaluation of linearity in the mass spectrometer by injecting the natural abundance compound at different concentration levels, (2) determination of the purity of the mass cluster using the natural abundance analogue, (3) calculation of the theoretical isotope composition of the labelled compound using different tentative isotope enrichments, (4) calculation of 'convoluted' isotope distributions for the labelled compound taking into account the purity of the mass cluster determined with the natural abundance analogue and (5) comparison of the isotope distributions measured for the labelled compound with those calculated for different isotope enrichments using linear regression. The method was applied to a series of commercially available (13)C- and (2)H-labelled compounds and to a suite of singly (13)C-labelled β2-agonist prepared in-house both by gas chromatography (GC)-MS, GC-tandem MS (MS/MS) and liquid chromatography-MS/MS with satisfactory results. It was observed that the main uncertainty source for the isotope enrichment was the uncertainty in the purity of the measured cluster as determined with the natural abundance compound.

Preparation of stir cake sorptive extraction based on poly(4-vinylbenzoic acid-divinylbenzene) monolith and its application in sensitive determination of β-agonists in milk and swine urine samples

In this study, a new stir cake sorptive extraction (SCSE) based on poly(4-vinylbenzoic acid-divinylbenzene) (VBADB) monolith was prepared. The effect of preparation conditions of monolith on extraction efficiencies was investigated in detail. Several characteristic techniques, such as elemental analysis, infrared spectroscopy, mercury intrusion porosimetry and scanning electron microscopy were used to characterize the monolithic material. The combination of SCSE-VBADB with high-performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS) detection was developed for sensitive determination of ultra-trace β-agonists in milk and swine urine samples. In order to obtain the optimal extraction conditions of SCSE-VBADB for β-agonists, several extractive parameters, including pH values and ionic strength in sample matrix, extraction and desorption time were optimized. Under the optimum conditions, the limits of detection (S/N=3) for the target analytes were 0.007-0.030 μg/L in milk and 0.002-0.011 μg/L in swine urine, respectively. Excellent method reproducibility was achieved in terms of intraday and interday precisions, indicated by the RSDs of both <10.0%, respectively. Finally, the proposed method was successfully used to detect β-agonists in different milk and swine urines samples. Acceptable recoveries ranged from 50.3% to 113% and 50.1% to 92.2% for milk and swine urine samples, respectively; and the RSDs for reproducibility were less than 8.0% for target analytes in all real samples.

A novel electrochemical sensor for the analysis of β-agonists: the poly(acid chrome blue K)/graphene oxide-nafion/glassy carbon electrode

A novel modified electrode was constructed by the electro-polymerization of 4,5-dihydroxy-3-[(2-hydroxy-5-sulfophenyl)azo]-2,7-naphthalenedisulfonic acid trisodium salt (acid chrome blue K (ACBK)) at a graphene oxide (GO)-nafion modified glassy carbon electrode (GCE). The characterization of an electrochemically synthesized poly-ACBK/GO-nafion film was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques, and the results were interpreted and compared at each stage of the electrode construction. Electrochemical oxidation of eight β-agonists - clenbuterol, salbutamol, terbutaline, ractopamine, dopamine, dobutamine, adrenaline, and isoprenaline, was investigated by CV at the different electrodes. At the poly-ACBK/GO-nafion/GCE, the linear sweep voltammetry peak currents of the eight β-agonists increased linearly with their concentrations in the range of 1.0-36.0 ng mL(-1), respectively, and their corresponding limits of detection (LODs) were within the 0.58-1.46 ng mL(-1) range. This electrode showed satisfactory reproducibility and stability, and was used successfully for the quantitative analysis of clenbuterol in pork samples.

Participation of citral in the bronchodilatory effect of ginger oil and possible mechanism of action

The extract of ginger, the rhizomes of Zingiber officinale Roscoe (Zingiberaceae), has been reported to possess anti-hyperactivity and anti-inflammation on airway. The present study described brochodilatory activity of ginger oil and identified its active compound. Ginger oil was extracted by hydro-distillation. The compositions of ginger oil were analyzed by gas chromatography and mass spectrometer. Citral, eucalyptol and camphene were found to be the major components. Ginger oil and citral, but not camphene, suppressed rat tracheal contraction induced by carbachol (CCh). Consistent with previous report, eucalyptol showed a relaxing effect on rat airway. Since the content of eucalyptol in ginger oil was relatively low, the contribution of eucalyptol to the bronchodilatory effect of ginger oil was small. To elucidate the mechanisms responsible for the myorelaxing effect, propranolol (a β-adrenergic receptor antagonist), indomethacin (a COX inhibitor) and L-NAME (a NOS inhibitor) were used to block the inhibitory effects of ginger oil and citral. It was found that propranolol, but not indomethacin and L-NAME, reversed bronchodilatory effects of both ginger oil and citral, suggesting that a possible mechanism involved β-adrenergic receptor. This study provides the pharmacological basis supporting the therapeutic potential of Z. officinale rhizomes as a bronchodilator.

Hair analysis, a reliable and non-invasive method to evaluate the contamination by clenbuterol

The illegal use of clenbuterol has been an increasingly serious issue in today's livestock products industry. It becomes an important project to develop a reliable approach to detect its content in food animals. A simple and sensitive LC-MS/MS method was developed to detect clenbuterol residue in hair, with the low limit of quantitation (LLOQ) about 0.5ng/g. Hogs fed with 340µg/day of clenbuterol for 2 weeks were found a high clenbuterol residue in their hair approximately at 1-2 months after withdrawal. There remained 3.31ng/g clenbuterol in hog hair approximately 5 months after the last administration, focused on the tip of the hair (mainly in hogs with dark hair). An extensive contamination was observed in twenty investigated market hogs whose dark hair obviously had a higher clenbuterol residue than the light ones (p=0.017, t test). Volunteers (60.3 percent) from Xuhui district (Shanghai) were found to have a detectable amount of clenbuterol in their hair (>0.5ng/g). In conclusion, hair residue detection is a reliable method to evaluate the clenbuterol contamination in animals and humans. Meat supply in the Xuhui district might have serious potential safety risks which should be further investigated and discussed to determine the safety range of clenbuterol residue.

Matrix effects in analysis of β-agonists with LC-MS/MS: influence of analyte concentration, sample source, and SPE type

The synergistic influences of analyte concentration, sample source, and solid-phase extraction (SPE) type on matrix effects in the multiresidue analyses of eight β-agonists with LC-ESI-MS/MS were evaluated. Porcine muscle and liver extracts and urine from diverse sources were purified by strong or mixed-mode cation exchange and molecularly imprinted polymer SPE cartridges, respectively. Three spiked concentrations (2, 10, and 20 ng/mL) of eight β-agonists in the purified matrices and the different sample sources were analyzed. The results show that for most β-agonists there are significant differences in matrix effects between analyte concentrations or sample sources (P < 0.05), whereas there is no significant difference in matrix effects between different SPE cartridges (P > 0.05). Results from main effects testing indicated that analyte concentration was the main effector.

Adsorption of beta-adrenergic agonists used in sport doping on metal nanoparticles: a detection study based on surface-enhanced Raman scattering

The adsorption of beta(2)-adrenergic agonist (βAA) drugs clenbuterol, salbutamol, and terbutaline on metal surfaces has been investigated in this work by means of surface-enhanced Raman scattering (SERS). To assist in this investigation, a previous vibrational (IR and normal Raman) characterization of these drugs was performed, supported by ab initio density functional theory calculations. The application of SERS was aimed to apply this highly sensitive technique, based on localized surface plasmon resonance, in the detection of βAA at trace concentrations and as a possible alternative method which can be postulated in routine antidoping analysis. The adsorption of these drugs was studied in depth at different experimental conditions: on Au and Ag, at different pHs, and with varying adsorbate concentration. Moreover, plasmon resonance spectroscopy was employed to investigate the adsorption of these drugs on the metal nanoparticles as well as their aggregation. It was found that the adsorption of these molecules is more effective on gold nanoparticles and at acidic pH, based on the direct interaction of the aromatic or aliphatic moieties through ionic or coordination bonds with the metal. These drugs followed a Langmuir adsorption model from which the adsorption constant and the limit of detection can be determined.

Preparation of anti-salbutamol antibody based on a new designed immunogen and development of a heterologous indirect ELISA for detection of salbutamol residue

To synthesize salbutamol immunogen and develop an enzyme immunoassay (ELISA), a new salbutamol immunogen was synthesized using 4-aminobenzoic acid as a linker to connect hapten with carrier protein. An enzyme immunoassay based on the antibody prepared was developed and applied to detect salbutamol residue spiked in swine liver. An unusual coating antigen, clenbuterol-ovalbumin (OVA) conjugate instead of salbutamol-OVA conjugate, was used in the immunoassay and the results were discussed based on the structures of related compounds. The antibodies showed high sensitivity in the heterologous assay when using clenbuterol-OVA as a coating antigen, with an IC50 value of 8.97 ng mL(-1) toward salbutamol. The antibodies prepared showed high cross-reactivity with clenbuterol (107%) and were promising for the simultaneous determination of salbutamol and clenbuterol residues in food and food products. Recovery rates from the salbutamol-spiked swine liver samples were in the range of 70%-99%, while the intra-assay and inter-assay coefficients of variation were <13.3% and <14.3%, respectively. In summary, the antibodies of salbutamol have been successfully prepared. Sensitive and stable analysis for the detection of salbutamol residues in swine liver was obtained based on the competitive ELISA methods developed in this study.

The β-agonist clenbuterol in mane and tail hair of horses

REASONS FOR PERFORMING STUDY

The beta2-agonist clenbuterol is commonly administered for therapeutic purposes in the horse, but its use an an anabolic agent is illegal. Clenbuterol can be detected in blood and urine for a relatively short period after administration and detection in hair could enhance the analytical range and be used to determine the history of clenbuterol application.

HYPOTHESIS

That detection in mane or tail hair is possible over an extended period.

METHODS

Four horses received 0.8 microg clenbuterol hydrochloride/kg bwt b.i.d. for 10 days. Four other horses were used as untreated controls. Blood, urine, mane and tail hair samples were taken on Day 0 (before) and 5, 10, 30, 35, 40, 60, 90, 120, 150 and 360 days after start of treatment. Gas chromotography/high resolution mass spectrometry (GC/HRMS) was developed for clenbuterol analysis: limit of detection was 0.2 pg/mg; intra-assay repeatability limit r = 0.06 (confidence level 95%); interassay repeatability limit r = 0.03 (confidence level 95%). Prior to treatment, clenbuterol was absent from all samples analysed.

RESULTS

Clenbuterol was detectable as early as Day 5 in tail and mane hair of Segment 1 (0-20 mm from the roots) and was maximal on Day 90. However, as time progressed, shift into lower 20 mm segments was observed. On Day 360, the maximum concentration (up to 21 pg/mg) was located in Segment 13, i.e. 26-28 cm from roots of hair. Clenbuterol was not detectable in blood or urine after Day 30. Mane and tail hair results were very similar.

CONCLUSIONS

The study showed that the beta-agonist clenbuterol can be found in mane and tail hair of horses after extended periods.

POTENTIAL RELEVANCE

It will be possible to detect clenbuterol in breeding and show horses where anabolic drugs have been used illegally to improve conformation. This method may also be helpful to monitor therapeutic clenbuterol treatment.

beta-Adrenergic stimulation

Two groups of substances which stimulate the adrenergic system are listed as prohibited by the World Anti-Doping Agency. Stimulants are prohibited in-competition only and beta(2)-agonists are prohibited in- and out-of-competition. While beta(2)-agonists act directly on the target receptors, sympathomimetic amines can exert their action directly and indirectly. Due to differences in pharmacology but mainly due to differences in administered dose, differences in detection methods between both groups of substances exist although preparation is similar and consists of an extraction at basic pH. Gas chromatography coupled to mass spectrometry has been the detection methodology of choice for several decades. However, the importance of liquid chromatography-mass spectrometry as a preferred detection methodology is rapidly increasing, especially for the detection of beta(2)-agonists and new additions to the list of prohibited stimulants, such as modafinil. Pharmacology, metabolism and detection of both groups of prohibited substances will be discussed.

Integrated microfluidic immunoassay for the rapid determination of clenbuterol

An integrated microfluidic immunoassay system was established for high throughput analysis of clenbuterol. This system consisted of an integrated microchip and a linear confocal laser induced fluorescence (LIF) scanner. The microchip was composed of three layers: a fluidic channel layer, a PDMS membrane layer and a pneumatic control layer. The multi-layer chip was integrated with 36 pneumatic micro-valves and multiple micro-pumps to realize the flexible reagent delivery, facilitating the automatic assays with less consumption of samples and reduced analysis time. The homemade LIF scanner was able to simultaneously detect multi-channels and provide the potential capability of high throughput assays. The performance of the system was demonstrated by the determination of clenbuterol, one of the most widely used beta-agonists. Under the optimal conditions, the linear range and the limit of detection of clenbuterol were 0 approximately 5.0 ng mL(-1) and 0.088 ng mL(-1), respectively. The recovery rates determined with pig urine samples of 1.0 ng mL(-1) and 2.0 ng mL(-1) were 98.74% and 102.51% (n = 3), respectively. The total detection time was less than 30 min. The system had the potential application for rapid detection of multiple beta-agonists in clinical, pharmaceutical and chemical analyses.

[Simultaneous determination of nine beta-agonist residues in animal derived foods by ultra performance liquid chromatography-tandem mass spectrometry]

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS) method was established for the simultaneous determination of terbutaline, cimaterol, salbutamol, fenoterol, clorprenaline, ractopamine, clenbuterol, tulobuterol, penbutolol residues in animal derived foods. After enzymolysis, the samples were extracted by perchloric acid, centrifuged, neutralized, followed by liquid-liquid extraction with ethyl acetate and tert-butyl methyl ether, separately. The combined extracts were applied to a solid phase extraction MCX cartridge for cleanup. The separation of beta-agonists was performed on Waters Acquity UPLC system with a BEH C18 column (50 mm x 2.1 mm, 1.7 microm) and the gradient elution solvent of acetonitrile (containing 0.1% formic acid) and water (containing 0.1% formic acid) at a flow rate of 0.3 mL/min. The method was quantified by external standard method. The calibration curves were good linear between the peak areas and the concentrations of 0.25 - 5 microg/kg with the correlation coefficient r > 0.990. The limit of detection of the 8 beta-agonists was 0.1 microg/kg, and the limit of quantification was 0.25 microg/kg. The limit of detection of penbutolol was 0.25 microg/kg, and the limit of quantification was 0.5 microg/kg. The average recoveries from spiked animal tissues at three concentrations of 0.5, 1 and 2 microg/kg ranged 87.1% - 108.6%. The relative standard deviations of intra- and inter-batch were both less than 20%.

[Determination of beta-adrenergic agonists in pig urine and pig fodder using miniaturized capillary electrophoresis with electrochemical detection]

A method of miniaturized capillary electrophoresis with electrochemical detection has been developed for the determination of beta-adrenergic agonists in pig urine and pig fodder. Several important factors, including running buffer acidity, separation voltage, working electrode potential, etc., were evaluated to acquire optimum analysis conditions. Under the selected optimum conditions, these analytes can be well separated in 7 min. Good linear relationship was established between the peak current and the concentration of each analyte over 3 orders of magnitude. The detection limits ranged from 1.20 x 10(-7) to 2.06 x 10(-7) g/mL (S/N = 3). The proposed method has been successfully applied for the determination of beta-adrenergic agonist in pig urine and pig fodder with satisfactory results, providing a useful monitoring method for food safety.

[Multi-residue analysis of 10 beta2-agonists in animal tissues using gas chromatography-mass spectrometry]

A method for multi-residue analysis of beta2-agonists, mabuterol, terbutaline, carbuterol, clenbuterol, cimaterol, salbutamol, clenpenterol, isoxsuprine, bambuterol and ractopamine in animal tissues using gas chromatography-mass spectrometry, based on isotope dilution and solid phase extraction has been developed. The homogenized sample was spiked with isotope-labeled internal standards, D9-clenbuterol, D3-salbutamol and D5-ractopamine, extracted with anhydrous alcohol, defatted using hexane, and cleaned-up on an SLS cartridge, and derivatized with N, O-bis (trimethylsilyl) trifluoro acetamide (BSTFA) + 1% trimethylchlorosilane (TMCS). The experimental results indicated that the recoveries were 72.8%-110.3%, and the relative standard deviations were 1.2%-11.3% in blank samples spiked with the above mentioned agonists at 2.0-10.0 microg/kg, and the corresponding detection limits were 0.5-1.0 micro/kg.

Development of an analytical method for the determination of beta2-agonist residues in animal tissues by high-performance liquid chromatography with on-line electrogenerated [Cu(HIO6)2]5- -luminol chemiluminescence detection

A novel method was developed for the simultaneous determination of beta2-agonist residues such as terbutaline, salbutamol, and clenbuterol by high-performance liquid chromatography (HPLC) coupled with chemiluminescence (CL) detection. The procedure was based on the enhancement effect of beta2-agonists on the CL reaction between luminol and the complex of trivalent copper and periodate ([Cu(HIO6)2]5-), which was on-line electrogenerated by constant current electrolysis. The HPLC separation used a Nucleosil RP-C18 column (250 mm x 4.6 mm i.d., 5 microm; pore size, 100 A) with a mobile phase consisting of 90% acetonitrile and 10% aqueous ammonium acetate (20 mmol L-1, pH 4.0) at a flow rate of 1.0 mL min-1. The effects of several parameters on the HPLC resolution and CL emission were studied systematically. Liver samples were hydrolyzed with beta-glucuronidase followed by a solid-phase extraction procedure using Waters OasisMCX cartridges. Under optimum conditions, the limits of detection at a signal-to-noise ratio of 3 ranged from 0.007 to 0.01 ng g-1 and the limits of quantification at a signal-to-noise ratio of 10 ranged from 0.023 to 0.033 ng g-1 for three beta2-agonists. The relative standard deviations (RSDs) of intra- and interday precision were below 4.5%. The average recoveries for beta2-agonists (spiked at the levels of 0.05-5.0 ng g-1) in pig liver ranged from 84 to 110%, and the RSDs of the quantitative results were from 1.6 to 7.2%. The proposed method was successfully applied to the determination of beta2-agonist residues in pig liver samples.

Simultaneous determination of salbutamol sulphate, bromhexine hydrochloride and etofylline in pharmaceutical formulations with the use of four rapid derivative spectrophotometric methods

Four simple, rapid, accurate, precise, reliable and economical spectrophotometric methods have been proposed for simultaneous determination of salbutamol sulphate (SS), bromhexine hydrochloride (BH) and etofylline (ET) in pure and commercial formulations without any prior separation or purification. They were first derivative zero crossing spectrophotometry (method 1), simultaneous equation method (method 2), derivative ratio spectra zero crossing method (method 3) and double divisor ratio spectra derivative method (method 4). The ranges for SS, BH and ET were found to be 1-35 microg mL(-1), 4-40 microg mL(-1) and 5-80 microg mL(-1). For methods 1 and 2, the values of limit of detection (LOD) were 0.2314 microg mL(-1), 0.4865 microg mL(-1) and 0.2766 microg mL(-1) and the values of limit of quantitation (LOQ) were 0.7712 microg mL(-1), 1.6217 microg mL(-1) and 0.9221 microg mL(-1) for SS, BH and ET, respectively. For method 3, LOD values were 0.3297 microg mL(-1), 0.2784 microg mL(-1) and 0.7906 microg mL(-1) and LOQ values were 0.9325 microg mL(-1), 0.9282 microg mL(-1) and 2.6352 microg mL(-1) for SS, BH and ET, respectively. For method 4, LOD values were 0.3161 microg mL(-1), 0.2495 microg mL(-1) and 0.2064 microg mL(-1) and LOQ values were 0.9869 microg mL(-1), 0.8317 microg mL(-1) and 0.6879 microg mL(-1) for SS, BH and ET. The precision values were less then 2% R.S.D. for all four methods. The common excipients and additives did not interfere in their determinations. The results obtained by the proposed methods have been statistically compared by means of Student t-test and by the variance ratio F-test.

Development and Identification of Monoclonal Antibodies Against Ractopamine

Ractopamine was reacted with two carrier proteins, human serum albumin and bovine thyroglobulin, as immunogen and coating antigen, respectively. Using a conventional immunization protocol, we generated a stable murine monoclonal antibody toward ractopamine, which had high affinities. The clone was found to be of IgG(2a) subclass with kappa light chain. An indirect competitive enzyme-linked immunosorbent assay for the determination of ractopamine has been optimized and characterized. The sensitivity, estimated as the IC(50) value, was 21.25 ng/mL, with a practical working range between 2.9 and 450 ng/mL. The limit of detection was 1.5 ng/mL. Moreover, other phenethanolamine beta-agonists showed low cross-reactivity with the monoclonal antibody. In addition, the indirect competitive enzyme-linked immunosorbent assay for the detection of ractopamine in animal feed was also developed using this antibody.

Ex vivo formation of gastric metabolites of clenbuterol: Preliminary characterisation of their chemical structure

The epidemiology of clenbuterol food-borne intoxication outbreaks indicates a possible discrepancy between the severity and long duration of clinical symptoms, and the presumed dose ingested as parent compound residue. In this work, we explore the possibility that clenbuterol could undergo to a biological transformation, in presence of salivary nitrites, at gastric pH (< 3). Human salivary specimens were drawn before and after meal, accounting for the different physiological nitrite content (40 and 400 micromol L(-1), respectively, as average). Clenbuterol (10 micromol L(-1)) was then incubated within the pH range 2-6 and possible products monitored by liquid chromatography-mass spectrometry (LC-MS), drawing at regular intervals serial aliquots of the incubation mixture. With respect to controls, two differential peaks were noted along with a quantitative bio-transformation of the parent compound, at pH values < or = 3. Under pre-meal conditions, a 4 mono-nitro compound was identified as main metabolite, whereas under post-meal condition a second metabolite, showing a complete de-chlorination, along with the probable presence of three nitro groups on the aromatic ring, was revealed. The reaction was highly reproducible and the kinetics suggested the involvement of nitrogen-related free radicals. The results are discussed in the light of the possible formation of pharmacological active tissue-bound residues as cause of symptoms severity.

Application of an enzyme-linked immunosorbent assay for the detection of clenbuterol residues in swine urine and feeds

The present study outlines applications of an enzyme-linked immunosorbent assay (ELISA) for the analysis of clenbuterol residues. Antisera were raised from rabbits immunized with diazotized clenbuterol-bovine serum albumin (BSA) conjugate. The assay was specific to clenbuterol with a half-maximum inhibition concentration (IC(50)) of 1.8 ng/mL and 2.5 ng/mL in blank swine urine and phosphate buffer solution, respectively. The assay had high cross-reactivity (86%) with mabuterol, but low with other adrenergic agonists and antagonists. The average recovery of clenbuterol, as measured with the ELISA, ranged from 90% to 112% in swine urine samples and from 86% to 95% in feeds, respectively. This new assay was compared with commercial ELISA test kits. An excellent correlation (r(2) = 0.98) between the two methods and satisfactory recoveries suggest that the new assay can be suitable for the determination of clenbuterol residues in real samples. The assay was used to analyze clenbuterol residues in 103 swine urine samples and 68 feed samples collected from northern China. Approximately 50% of the urine samples and 25% of the feed samples analyzed were found positive (concentration of clenbuterol > or = 1 ppb). The results indicate that clenbuterol was misused in some of the areas surveyed.

The occurrence and removal of selected pharmaceutical compounds in a sewage treatment works utilising activated sludge treatment

Pharmaceutical substances have been detected in sewage effluents as well as receiving waters in many parts of the world. In this study, the occurrence and removal of a number of drug compounds were studied within a large sewage treatment plant in the south of England. Samples were processed using solid phase extraction and analysed using gas chromatography-mass spectrometry (GC-MS). The results demonstrate that ibuprofen, paracetamol, salbutamol and mefenamic acid were present in both the influent and effluent of the works while propranolol-HCl was not found above the limit of quantification in any sample. Elimination rates were circa 90% for each compound but several hundred nanograms per litre were still present in the final effluent.

Quantification of Terbutaline in Pharmaceutical Formulation and Human Serum by Adsorptive Stripping Voltammetry at a Glassy Carbon Electrode

The electrochemical oxidative behavior of terbutaline at the glassy carbon electrode was studied in a series of the Britton-Robinson buffer of pH 2--11. Cyclic and square-wave voltammograms of terbutaline at the pH values </=9 exhibited a single irreversible anodic peak. A fully validated, simple, sensitive and precise square-wave adsorptive anodic stripping voltammetric procedure was described for the determination of terbutaline in bulk form, tablets and human serum. For 5x10(-8) M bulk terbutaline a mean recovery of 98.78+/-0.94% (n=5) was achieved following its preconcentration by adsorptive accumulation onto the glassy carbon electrode at a +0.15 V (vs. Ag/AgCl/KCl(s)) for 180 s. Limit of detection of 6x10(-9) M and limit of quantitation of 2x10(-8) M terbutaline were achieved in the bulk form or its formulations (Bricanyl tablets). The described square-wave adsorption anodic stripping voltammetric procedure was successfully applied for the determination of terbutaline in human serum following medium exchange. Limit of detection of 1.41x10(-8) M (3.173 ng ml(-1)) and limit of quantitation of 4.70x10(-8) M (10.575 ng ml(-1)) were achieved in human serum with a mean recovery of 98.11+/-1.13%.

Development of a lateral-flow assay for rapid screening of the performance-enhancing sympathomimetic drug clenbuterol used in animal production; food safety assessments

A lateral-flow assay that could provide visual evidence of the presence of clenbuterol in swine urine was developed. Colloidal gold was prepared and conjugated with anti-clenbuterol monoclonal antibody. Immunochromatographic test strips were produced, and then, 210 samples were tested on these strips. Analysis was completed in 10 min. Detection limit was 3 ppb of clenbuterol. Parallel GC-MS data indicated that clenbuterol rapid detection strip had no false negative. The false positive rate was 4.4%. Immunochromatographic strip has great applied value in the food safety field because it possesses benefits of sensitivity, stability, reproducibility, ease of use and inexpensive.

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.

Bioluminescence resonance energy transfer as a screening assay: Focus on partial and inverse agonism

The reported data for compound screening with the bioluminescence resonance energy transfer (BRET2) assay is very limited, and several questions remain unaddressed, such as the behavior of agonists. Eleven beta2 adrenergic receptor (beta2-AR) agonists were tested for full or partial agonism in an improved version of the receptor/beta-arrestin2 BRET2 assay and in 2 cyclic adenosine monophosphate (cAMP) assays (column cAMP assay and ALPHAscreen cAMP assay). Tested in the highly sensitive ALPHAscreen cAMP assay, all selected agonists behaved as full agonists, using isoproterenol as a reference compound. In the less sensitive column cAMP assay, ephedrine and dopamine had a clear partial response. For the BRET2 assay, a highly graded picture was obtained. Moreover, beta2-AR antagonists were tested for inverse agonism. Pronounced inverse agonism was detected in the ALPHAscreen cAMP assay. Only marginal inverse agonistic responses were seen for alprenolol and pindolol in the column cAMP assay, and no inverse agonism was seen in the BRET2 assay. For the beta2-AR, the BRET2 assay may be superior for secondary screening of agonists where a separation of full and partial agonists is needed and the ALPHAscreen cAMP assay may be preferred for primary screening of agonists where all receptor activating compounds are desired.

Factorial design applied to a non-aqueous capillary electrophoresis method for the separation of β-agonists

The aim of this work was to study the effects of both chemical and instrumental parameters on the separation of beta-agonists (clenbuterol (CLE), salbutamol (SAL) and terbutaline (TER)) by non-aqueous capillary electrophoresis (NACE) method. Due to the number of parameters involved and their interactions, factorial experimental designs (EDs) at two levels was applied to investigate the influence of experimental factors (ionic strength of the background electrolyte (BGE), organic solvent, injection time, voltage and temperature) in sets of several CE responses (resolution, (RS), number of theoretical plate (N), tailing factor (TF) and migration time (tm)). As a compromise between the four responses, the optimum condition was obtained in 18 mM ammonium acetate in methanol (MeOH):acetonitrile (ACN):glacial acetic acid (66:33:1%, v/v/v) using an injection time of 4 s, the voltage and the temperature of 28 kV and 24 degrees C, respectively. The proposed NACE permitted the baseline separation of the three beta-agonists within 10.5 min with good repeatability (%RSD < 3.5%) and linearity (r2 > 0.99). The developed method was applicable for the analysis of the beta-agonists in syrup and tablets and the NACE condition was compatible with a mass spectrometer detector.

Optimization of capillary electrophoretic enantioseparation for basic drugs with native β-CD as a chiral selector

This study presents the advantages of the 20 microm inner diameter (id) capillary for the enantioseparation of ten basic drugs with native beta-CD as the chiral selector. The apparent binding constants of each enantiomeric pair were determined to calculate the optimum beta-CD concentration ([beta-CD]opt) and the optimization was subsequently carried out. Comparison of the 20 microm id with 50 microm id were made in terms of the results obtained in the optimization and detection limits. Applying the optimum conditions for each compound, reproducible results (RSD from 0-3; n>5) were obtained for the 20 microm id capillary. Although the sensitivity is lower in the 20 microm id capillary, the LOD determined using this capillary is still found to be acceptable for the ten basic drugs studied. Enhanced resolution and faster analysis times were the main advantages observed with the use of this capillary in enantioseparation.

Technical Note: A monoclonal antibody-based immunoassay for determination of ractopamine in swine feeds1

An ELISA was developed for routine screening of ractopamine in swine feeds. Swine feed samples were extracted and purified, and the aqueous portion of the extract was analyzed for ractopamine using ELISA and confirmed by HPLC. For swine complex feeds containing ractopamine at 2.5 to 40 mg/kg, the average recoveries ranged from 73.1 to 86.5% by ELISA and 81.9 to 98.2% by HPLC. For the swine supplement containing ractopamine at 50 to 400 mg/kg, the average recoveries were 105.5 to 111.4% by ELISA and 89.1 to 92.9% by HPLC. The limit of detection was 0.24 microg/g by ELISA and 0.48 microg/g by HPLC, respectively. Results from the swine complex feeds (P = 0.009) and the supplement (P = 0.005) using ELISA and HPLC were not highly correlated. The ELISA was more sensitive and rapid and less expensive than the HPLC method and could be used for ractopamine screening in swine feeds before confirmation and quantification by other methods, such as HPLC.

Utilization of 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) for kinetic spectrophotometric assay of befunolol hydrochloride in its pharmaceutical formulation

A simple, accurate, precise, and sensitive kinetic spectrophotometric method for determination of befunolol hydrochloride is described. The method is based on the formation of a colored product with 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) in methanol at 70 degrees C for 45 min. The red-colored product was measured at 523 nm. The optimization of various experimental conditions is described; Beer's law was obeyed in the range 15.25 x 10(-6) to 122.04 x 10(-6) M. The results obtained showed good recoveries (100.1 +/- 0.80%). Application of the proposed method to a pharmaceutical formulation was successfully achieved. The determination of befunolol hydrochloride by fixed time, fixed concentration, and rate constant methods was feasible with the calibration equation obtained. However, the fixed time method proved to be more applicable.

Determination of salbutamol in syrups by capillary electrophoresis with contactless conductivity detection (CE-C4D)

This paper describes the separation and quantification of salbutamol in pharmaceutical products (salbutamol syrups) by capillary electrophoresis (CE) with contactless conductivity detection (C(4)D). The system was studied by micellar electrokinetic capillary chromatography (MEKC) and free solution capillary electrophoresis (FSCE), being the latter chosen in function of best resolution and sensitivity in comparison with the MEKC method. CE-C(4)D was applied to analysis of salbutamol in syrups utilizing 1.0 x 10(-2) molL(-1) acetic acid/sodium acetate buffer (pH 4.9) as running electrolyte. Tetraethylammonium (TEA) solution was used as internal standard. The results obtained include a linear dynamic range from 7. x 10(-5) to 3.0 x 10(-4) molL(-1) and good repeatability (R.S.D.=4.7% for n=10 for a 7.0 x 10(-5) molL(-1) salbutamol solution). The detection limit was calculated as 1.0 x 10(-5) molL(-1) and the limit of quantification was estimated as 3.3 x 10(-5) molL(-1). For syrups analysis the reproducibility presented deviations between 1.5% and 2.5% (three different days) obtained for measurements in triplicate.

Improving LC-MS sensitivity through increases in chromatographic performance: comparisons of UPLC-ES/MS/MS to HPLC-ES/MS/MS

Recent technological advances have made available reverse phase chromatographic media with a 1.7 microm particle size along with a liquid handling system that can operate such columns at much higher pressures. This technology, termed ultra performance liquid chromatography (UPLC), offers significant theoretical advantages in resolution, speed, and sensitivity for analytical determinations, particularly when coupled with mass spectrometers capable of high-speed acquisitions. This paper explores the differences in LC-MS performance by conducting a side-by-side comparison of UPLC for several methods previously optimized for HPLC-based separation and quantification of multiple analytes with maximum throughput. In general, UPLC produced significant improvements in method sensitivity, speed, and resolution. Sensitivity increases with UPLC, which were found to be analyte-dependent, were as large as 10-fold and improvements in method speed were as large as 5-fold under conditions of comparable peak separations. Improvements in chromatographic resolution with UPLC were apparent from generally narrower peak widths and from a separation of diastereomers not possible using HPLC. Overall, the improvements in LC-MS method sensitivity, speed, and resolution provided by UPLC show that further advances can be made in analytical methodology to add significant value to hypothesis-driven research.

Determination of albuterol sulfate and its related substances in albuterol sulfate inhalation solution, 0.5% by RP-HPLC

An isocratic reversed-phase high performance liquid chromatographic (RP-HPLC) method has been developed and validated for the determination of albuterol sulfate and six of its related substances in albuterol sulfate inhalation solution, 0.5% (w/v). The separation was achieved using a YMC phenyl column (250 mm x 4.6 mm ID, 5 microm fitted with a direct connect YMC phenyl guard column (20 mm x 4 mm ID) maintained at ambient conditions, and a mobile phase of 25 mM monobasic potassium phosphate (pH 3.0) and methanol (95:5, v/v). The mobile phase flow rate was 1.5 mL/min and the detection wavelength was 225 nm. Albuterol is quantitated versus an external standard. The method was capable of resolving six of the seven known albuterol-related substances. Bis-ether albuterol, a drug substance process related impurity, is retained on the column due to its different hydrophilic character. The related substances are determined by area percent. However, a correction factor of 1.6 is applied for the determination of albuterol aldehyde, a potential impurity and a degradation product, since its molar absorptivity is about 1.6 times that of albuterol. The limits of detection and quantitation for albuterol and six of its related substances ranged between 0.01 and 0.21% of the assay concentration of 0.3 mg/mL as albuterol base. The method was found to be linear for albuterol over the range of 50-150% of the active label claim. The method was also found to be linear for the six related substances over the range 0.05-0.5%. No interferences from the blank, placebo (formulation matrix), related substances or force-degraded placebo samples were observed for the determination of the active or the individual related substances. The method was found to be accurate, precise, linear, specific, sensitive, rugged, robust, and stability-indicating.

Determination of Salbutamol in Pharmaceuticals by Capillary Electrophoresis

A capillary electrophoresis (CE) method for the separation and determination of salbutamol (SAL) in commercial pharmaceuticals was developed. Several parameters affecting the separations were studied including type and concentration of the carrier ion, counter ion, and the pH of the buffer. A hydrodynamically closed CE separation mode employing a 300 mum I.D. capillary, dynamically coated by polymeric buffer additive, provided good performance parameters (precision, accuracy, sensitivity). The obtained results suggest that the proposed method is suitable for routine assay of SAL in pharmaceutical preparations and can be used as an alternative to the conventional open CE mode for this application.

Food poisoning by clenbuterol in Portugal

This paper describes the occurrence of four cases of acute food poisoning, involving a total of 50 people, due to the ingestion of lamb and bovine meat containing residues of clenbuterol. Symptoms shown by the intoxicated people may be generally described as gross tremors of the extremities, tachycardia, nausea, headaches and dizziness. Analytical methodology developed for the determination of clenbuterol in meat, liver and blood samples is described. Procedures are described which should be followed when the described symptoms are evident in a group of people who have ingested contaminated meat, and particularly liver of ruminants.

Development of a monoclonal antibody-based enzyme-linked immuosorbent assay for the beta-adrenergic agonist zilpaterol

Zilpaterol is a beta-adrenergic agonist approved for use as a growth promoter in cattle in South Africa and Mexico but not in the European Union, United States, or Asia. Here, we report the development of a monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) for zilpaterol. Mice immunized with zilpaterol-butyrate-keyhole limpet hemocyanin were utilized for monoclonal antibody generation whereas zilpaterol-butyrate-bovine serum albumin was used as a coating antigen for ELISA. Thirteen clones were isolated, and after the initial sensitivity and isotyping experiments, three clones were selected for further ELISA optimization. Studies indicated that the optimum pH was near 7.4. Clone 3H5 had the highest sensitivity to zilpaterol and some interaction with clenbuterol and terbutaline at high concentrations but not other N-alkyl [bamethane, (-)-isoproterenol, (+)-isoproterenol, metaproterenol, or salbutamol] or N-arylalkyl (fenoterol, isoxsuprine, ractopamine, or salmeterol) beta-agonists tested. However, clone 3H5 was not functional at high salt concentrations, which precluded further development for urine analysis. Clone 2E10 showed increased sensitivity as salt concentrations were increased and did not cross-react with any of the structural analogues tested. However, its sensitivity to salt and urine concentration changes could cause high variability. Clone 7A8 showed good sensitivity and only a modest change with the salt concentration changes. Clone 7A8 also demonstrated smaller changes in IC(50) and B(0) with increasing sheep urine or cattle urine concentrations as compared to clones 2E10 or 3H5 and, thus, was selected for further development. The IC(50) for all of the antibodies showed exponential increases with increasing organic solvents concentrations, making it desirable to minimize solvent levels. In conclusion, a sensitive, specific zilpaterol monoclonal antibody-based ELISA has been developed that can serve as a rapid screening assay.

Sensitive detection of salbutamol using europium-enhanced fluorescence with trioctylphosphine oxide (TOPO) as coligand

In this work a simple and sensitive fluorimetric method for determination of salbutamol (4-[2-(tert-butylamino)-1-hydroxyethyl]-2-(hydroxymethyl) phenol) using an Eu enhanced signal was developed. The employed methodology is based on the formation of a ternary complex formed with Eu, salbutamol and trioctylphosphine oxide (TOPO). Intermolecular transfer of energy from the excited organic molecule to the lanthanide followed by lanthanide emission is responsible for excitation of the lanthanide ion in complex solutions and fluorescent enhancement. The luminescence properties of the ternary complex formed with TOPO and optimum formation conditions were investigated. The calibration curve is linear in the range between 6.92-180 microg l(-1) of salbutamol. The detection limit was 2.31 microg l(-1). Common excipients for these formulations were not found to interfere. A proposed method for the assay in commercial aerosols and nebulizer solutions containing salbutamol was applied with very good precision.