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

Isocratic ion pair chromatography for estimation of novel combined inhalation therapy that blocks coronavirus replication in chronic asthmatic patients

A rapid and sensitive isocratic ion-pair chromatographic method was developed for the accurate analysis of ternary mixtures of formoterol, tiotropium, and ciclesonide in their novel combined inhalation that is widely used for the symptomatic treatment of patients with chronic obstructive disease. Analytical separation was performed using a C₈ column and ion pair mobile phase composed of acetonitrile: acidified deionized water (55: 45% v/v) containing 0.025% sodium dodecyl sulfate. The pH was adjusted to 3.0 using orthophosphoric acid and eluted isocratically at 2.0 mL/min and 40 °C applying UV detection at 237 nm. The calibration ranges were found to be 0.3-9.0 µg/mL for formoterol, 0.45-13.5 µg/mL for tiotropium, and 10.0-300.0 µg/mL concerning ciclesonide. The proposed method exhibited good repeatability, accuracy, and sensitivity (R.S.D. < 2.0%). The approach is rapid (run time does not exceed 15 min) and achieves satisfactory resolution (resolution factors = 7.45 and 5.3 between formoterol and tiotropium and tiotropium and ciclesonide respectively). The sensitivity and the efficiency of the proposed method permit their successful estimation with a recovery percentage ± SD of 99.33% ± 0.43 for formoterol, 99.15% ± 0.60 for tiotropium, and 99.90% ± 0.41 for ciclesonide.

Simple and Sensitive Analysis of Clenbuterol in Urine Matrices by UHPLC-MS/MS Method with Online-SPE Sample Preparation

Clenbuterol is one of the most misused anabolic agents in professional sports. Therefore, the monitoring of clenbuterol in body fluids such as human urine is related to the development of rapid, selective and sensitive analytical methods that produce reliable results. In this work, these requirements were met by a two-dimensional separation method based on online solid-phase extraction coupled with ultra-high performance liquid chromatography–tandem mass spectrometry (SPE–UHPLC–MS/MS). The developed method provides favorable performance parameters, and it is characterized by minimum manual steps (only dilution and the addition of an internal standard) in the sample preparation. A limit of quantification (LOQ) of 0.1 ng/mL, excellent linearity (0.9999), remarkable precision (1.26% to 8.99%) and high accuracy (93.1% to 98.7%) were achieved. From a practical point of view, the analytical performance of the validated SPE–UHPLC–MS/MS method was demonstrated on blinded spiked urine samples from ten healthy volunteers. The estimated concentrations of clenbuterol were in accordance with their corresponding nominal values, as supported by the precision and accuracy data (relative standard deviation ≤5.4%, relative error ≤11%). The fulfillment of the World Anti-Doping Agency’s screening and confirmation criteria indicates that the proposed method is suitable for implementation in routine use in toxicologic and antidoping laboratories. Due to its high orthogonality and separation efficiency, the SPE–UHPLC–MS/MS method should also be easily adapted to the separation of structurally related compounds (such as clenbuterol metabolites). Thus, future antidoping applications could also include monitoring of clenbuterol metabolites, providing a longer detection widow.

Doping in Racing Pigeons (Columba livia domestica): A Review and Actual Situation in Belgium, a Leading Country in This Field

Pigeon racing is a sport in which trained homing pigeons (Columba livia domestica) are released between 60 and 1200 km from their loft and then have to return home as quickly as possible. The first race was held in 1818 in Belgium and since then, Belgium has led the world in pigeon breeding. Unfortunately, as in other sports, doping has become a major issue and doping controls have been implemented. This review provides information about pigeon racing, rules from the Royal Federation Colombophile of Belgium, and laws applicable in Belgium as doping control issues cannot be understood without including them as part of pigeon racing. The main pharmacological data concerning corticoids, non-steroidal anti-inflammatory drugs, anabolic steroids, pain relievers and narcotic analgesics, bronchodilators and β-agonists, drugs acting on the central nervous system and other performance-enhancing drugs, in addition to methods relevant to doping in pigeons are presented. Moreover, the chosen matrix and analytical methods are described.

Determination of vitamin E and its metabolites in equine urine using liquid chromatography-mass spectrometry

Equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) is a hereditary, deteriorating central nervous disease in horses. Currently, the only way to confirm eNAD/EDM is through a postmortem histological evaluation of the central nervous system. Vitamin E, specifically the isoform alpha-tocopherol (α-TP), is known to protect eNAD/EDM susceptible horses from developing the clinical phenotype. While vitamin E is an essential nutrient in the diet of horses, there are no diagnostic tests able to quantitate vitamin E and its metabolites in urine. An ultra-performance liquid chromatography-atmospheric-pressure chemical ionization mass spectrometry (UPLC-APCI-MS/MS) method was developed and validated following acidic hydrolysis and solid phase extraction to quantitate vitamin E and its metabolites in equine urine. A blank control horse urine matrix was used and spiked with different concentrations of analytes to form a standard curve using either alpha-tocopherol-d6 or chlorpropamide as the internal standard. Inter-day and intra-day statistics were performed to evaluate the method for accuracy (90% to 116%) and precision (0.75% to 14%). Matrix effects, percent recovery, and stability were also assessed. The method successfully analyzed alpha-carboxyethyl hydroxychroman (α-CEHC), alpha-carboxymethylbutyl hydroxychromans (α-CMBHC), gamma-carboxyethyl hydroxychroman γ-CEHC, and α-TP concentrations in urine to determine a baseline levels of analytes in healthy horses, and can be used to determine concentrations of vitamin E metabolites in equine urine allowing for its evaluation as a diagnostic approach in the treatment of eNAD/EDM.

Doping detection in animals: A review of analytical methodologies published from 1990 to 2019

Despite the impressive innate physical abilities of horses, camels, greyhounds, or pigeons, doping agents might be administered to these animals to improve their performance. To control these illegal practices, anti-doping analytical methodologies have been developed. This review compiles the analytical methods that have been published for the detection of prohibited substances administered to animals involved in sports over 30 years. Relevant papers meeting the search criteria that discussed analytical methods aiming to detect and/or quantify doping substances in animal biological matrices published from 1990 to 2019 were considered. A total of 317 studies were included, of which 298 were related to horses, demonstrating significant advances toward the development of doping detection methods for equine sports. However, analytical methods for the detection of doping agents in sports involving other species are lacking. Due to enhanced accuracy and specificity, chromatographic analysis coupled to mass spectrometry detection is preferred over immunoassays. Regarding biological matrices, blood and urine remain the first choice, although alternative biological matrices, such as hair and feces, have been considered. With the increasing number and type of drugs used as doping agents, the analytes addressed in the published papers are diverse. It is very important to continue to detect and quantify these drugs, recognizing those that are most frequently used, in order to punish the abusers, protect animals' health, and ensure a healthier and genuine competition.

Development of in-house ELISA for detection of chloramphenicol in bovine milk with subsequent confirmatory analysis by LC-MS/MS

This study was undertaken to develop and validate direct competitive ELISA for the determination of chloramphenicol residues in bovine milk. Antisera and an enzyme-tracer for chloramphenicol were prepared and used to develop an ELISA with inhibition concentrations, IC₂₀ and IC₅₀, of 0.09 and 0.44 ng mL^-1, respectively. Milk samples were spiked with standards equivalent to 0, 0.2, 0.3, 0.5, 1.0 & 1.5 ng mL^-1 and extracted in methanol. The mean recoveries were found to be 73-100% with coefficient of variance 7-11%. The decision limit (CCα) and detection capability (CCβ) were calculated as 0.10 and 0.12 ng mL^-1, respectively. The results were found comparable with the commercial ELISA, having recoveries of 87 to 100%, CCα 0.09 ng mL^-1 and CCβ 0.12 ng mL^-1. As per Commission Decision 2002/657/EC, in-house ELISA was further validated by using LC-MS/MS. Mass spectral acquisition was done by using electrospray ionization in the negative ion mode applying single reaction monitoring of the diagnostic transition reaction for CAP (m/z 152, 194 and 257). The calibration curve showed good linearity in concentrations from 0.025 to 1.6 ng mL^-1 with correction coefficient 0.9902. The mean recoveries were found to be 88 to 100%. The CCα was calculated as 0.057 ng mL^-1 and CCβ 0.10 ng mL^-1. Since CCα and CCβ are less than half of the MRPL (0.15 ng mL^-1), the test was found suitable for screening and quantification of CAP residues in bovine milk samples. Results of surveillance studies indicated that out of 31 analyzed milk samples, 12.9% samples were found with CAP residues but only 3.2% samples were declared positive with maximum concentration 0.31 ng mL^-1, slightly above the MRPL.

Detection and pharmacokinetics of salmeterol in thoroughbred horses following inhaled administration

Salmeterol is a man-made beta-2-adrenergic receptor agonist used to relieve bronchospasm associated with inflammatory airway disease in horses. Whilst judicious use is appropriate in horses in training, they cannot race with clinically effective concentrations of medications under the British Horseracing Authority's Rules of Racing. Salmeterol must therefore be withdrawn prior to race day and pharmacokinetic (PK) studies used to establish formal detection time advice. Salmeterol xinafoate (Serevent Evohaler^® ) was administered (0.1 mg twice daily for 4.5 days) via inhalation to six horses. Urine and blood samples were taken up to 103 h postadministration. Hydrolysed samples were extracted using solid phase extraction. A sensitive Ultra high performance tandem mass spectrometry (UPLC-MS/MS) method was developed, with a Lower limit of quantification (LLOQ) for salmeterol of 10 pg/mL in both matrices. The majority of salmeterol plasma concentrations, postlast administration, were below the method LLOQ and so unusable for PK analysis. Urine PK analysis suggested a half-life consistent with duration of pharmacological effect. Average estimated urine concentration at steady-state was obtained via PK modelling and used to estimate a urine concentration of 59 ± 34 pg/mL as a marker of effective lung concentration. From this, potential detection times were calculated using a range of safety factors.

Simplifying and expanding analytical capabilities for various classes of doping agents by means of direct urine injection high performance liquid chromatography high resolution/high accuracy mass spectrometry

So far, in sports drug testing compounds of different classes are processed and measured using different screening procedures. The constantly increasing number of samples in doping analysis, as well as the large number of substances with doping related, pharmacological effects require the development of even more powerful assays than those already employed in sports drug testing, indispensably with reduced sample preparation procedures. The analysis of native urine samples after direct injection provides a promising analytical approach, which thereby possesses a broad applicability to many different compounds and their metabolites, without a time-consuming sample preparation. In this study, a novel multi-target approach based on liquid chromatography and high resolution/high accuracy mass spectrometry is presented to screen for more than 200 analytes of various classes of doping agents far below the required detection limits in sports drug testing. Here, classic groups of drugs as diuretics, stimulants, β₂-agonists, narcotics and anabolic androgenic steroids as well as various newer target compounds like hypoxia-inducible factor (HIF) stabilizers, selective androgen receptor modulators (SARMs), selective estrogen receptor modulators (SERMs), plasma volume expanders and other doping related compounds, listed in the 2016 WADA prohibited list were implemented. As a main achievement, growth hormone releasing peptides could be implemented, which chemically belong to the group of small peptides (<2kDa) and are commonly determined by laborious and time-consuming stand-alone assays. The assay was fully validated for qualitative purposes considering the parameters specificity, robustness (rRT: <2%), intra- (CV: 1.7-18.4 %) and inter-day precision (CV: 2.3-18.3%) at three concentration levels, linearity (R²>0.99), limit of detection (0.1-25ng/mL; 3'OH-stanozolol glucuronide: 50pg/mL; dextran/HES: 10μg/mL) and matrix effects.

In vivo metabolism study of (R)-bambuterol in humans using ultra high performance liquid chromatography with tandem mass spectrometry

(R)-Bambuterol, a selective β2-adrenoceptor agonist, has been approved as a new drug for the treatment of asthma and chronic obstructive pulmonary disease by the China Food and Drug Administration and is currently under phase I clinical trials. In this study, a combined method based on ultra high performance liquid chromatography with triple quadrupole mass spectrometry and ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry was employed for the identification of the major metabolites of (R)-bambuterol in human plasma and urine after an oral dose of 10 mg. The metabolites were separated by gradient elution program and different sample preparation methods were compared. Totally, 12 metabolites of (R)-bambuterol were identified, including four metabolites in plasma and all 12 metabolites in urine. Among these, four metabolites are reported for the first time. The possible metabolic pathways of (R)-bambuterol were subsequently proposed. The results indicated that (R)-bambuterol was metabolized via hydrolysis, demethylation, oxygenation, glucuronidation, and sulfation pathways in vivo. This study revealed that this combined method was accurate and sensitive to identify the possible metabolites and to better understand the metabolism of (R)-bambuterol in vivo.

Current status and recent advantages in derivatization procedures in human doping control

Derivatization is one of the most important steps during sample preparation in doping control analysis. Its main purpose is the enhancement of chromatographic separation and mass spectrometric detection of analytes in the full range of laboratory doping control activities. Its application is shown to broaden the detectable range of compounds, even in LC–MS analysis, where derivatization is not a prerequisite. The impact of derivatization initiates from the stage of the metabolic studies of doping agents up to the discovery of doping markers, by inclusion of the screening and confirmation procedures of prohibited substances in athlete's urine samples. Derivatization renders an unlimited number of opportunities to advanced analyte detection.

Simultaneous analysis of 210 prohibited substances in human urine by ultrafast liquid chromatography/tandem mass spectrometry in doping control

RATIONALE

Doping analysis is a two-step process consisting of a screening step for prohibited substances and a confirmation step to verify the presence of specific substances found during the screening. The entire process must be performed within a limited time period, but traditional screening procedures commonly employ separate analytical methods for each class of prohibited substances being screened and thus require a great deal of human resources and instrumentation. A single simple and rapid multiresidue analytical method that could accommodate multiple classes of prohibited substances would be extraordinarily useful in doping analyses.

METHODS

Urine samples were extracted via two consecutive liquid-liquid extractions at different pH values following enzymatic hydrolysis. Analyses were performed by ultrafast liquid chromatography/triple-quadrupole mass spectrometry with polarity switching and time-dependent selected reaction monitoring.

RESULTS

We developed a rapid multiresidue screening and confirmation method for efficient high-throughput doping analyses. The present method was validated with regard to the limits of detection (0.01-100.0 ng/mL for screening analyses and 0.2-500.0 ng/mL for confirmation assays), matrix effects (48.9-118.9%), recovery (20.6-119.7%) and intra- (0.6-17.6%) and inter-day (4.0-20.0%) precision.

CONCLUSIONS

A multiresidue analytical method was developed and validated for screening and confirming the presence of performance-enhancing drugs. A total of 210 substances from diverse classes of prohibited substances were successfully identified with an analytical run time of 10 min.

Pharmacokinetics of ractopamine and its organ distribution in rats

Ractopamine, a β-agonist, is used to increase the proportion of lean meat in livestock. However, due to potential cardiovascular risks, ractopamine has been banned for use in food-producing animals in many countries. Nevertheless, pharmacokinetic studies of ractopamine have not been completed. The aim of this study was to develop a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of ractopamine. This validated method was used to investigate the pharmacokinetics and organ distribution of ractopamine in rats. The validation results complied with the U.S. Food and Drug Administration's standards. The oral bioavailability of ractopamine was 2.99%. After intravenous administration, ractopamine concentrations varied as follows: kidney > lung > spleen > heart > liver > muscle > plasma > brain. Nonlinear pharmacokinetics and strong partitioning into tissues were observed after intravenous administration of ractopamine. These effects may be due to nonlinear elimination via the kidney.

Design of highly sensitive phosphorescence sensor for determination of procaterol hydrochloride based on inhibition of KClO3 oxidation fluorescein isothiocyanate

Procaterol hydrochloride (Prh) can inhibit KClO3 oxidation of fluorescein isothiocyanate (FITC) to form a non-phosphorescent compound, which causes room temperature phosphorescence (RTP) of FITC in the system to enhance sharply the linear relationship between ∆Ip and the Prh content. Thus, a rapid response and highly sensitive phosphorescence sensor for the determination of Prh has been developed based on the inhibiting effect of Prh on KClO3 oxidation of FITC. This simple, high sensitivity (detection limit (LD) calculated by 3Sb /k was 0.019 fg/spot, sample volume 0.40 µl, corresponding concentration 4.8 × 10(-14) g ml(-1) ) and selective sensor with a wide linear range (0.080-11.20 g/spot) has been applied to detect Prh in blood samples, and the results were consistent with those obtained by high-performance liquid chromatography (HPLC). Simultaneously, the mechanism of the phosphorescence sensor for the detection of Prh was also investigated using infrared spectroscopy.

Structural characterization of product ions by electrospray ionization and quadrupole time-of-flight mass spectrometry to support regulatory analysis of veterinary drug residues in foods

RATIONALE

Monitoring of veterinary drug residues in foods is often conducted using liquid chromatography/tandem mass spectrometry (LC/MS/MS). Results have high economic stakes for producers, but the ions monitored are usually selected due to signal intensities without structural interpretation. In this study, the ion transitions were characterized by high-resolution mass spectrometry.

METHODS

The 62 veterinary drugs from the LC/MS/MS method consisted of sulfonamides, β-lactams, phenicols, macrolides, tetracyclines, fluoroquinolones, non-steroidal anti-inflammatory drugs (NSAIDs), and corticosteroids. They were individually infused into a quadrupole time-of-flight (Q-TOF) mass spectrometer using electrospray ionization (ESI) operated in positive mode. The MS and collision-induced dissociation (CID) MS/MS spectra for each analyte were obtained for structural elucidation. The Q-TOF instrument was calibrated to obtain a mass accuracy error <5 ppm for the MS and MS/MS spectra.

RESULTS

The use of high-resolution ESI-Q-TOF-MS for the generation of the MS/MS product ions allowed for the determination of chemical formulae for the analytes, some of which led to new findings. Assigned structures were based on rational interpretation of the most stable possible products with comparison with the scientific literature. In difficult cases, isotopically labeled drugs or hydrogen/deuterium (H/D) exchange experiments were used to help confirm the structures of the product ions.

CONCLUSIONS

The use of ESI-Q-TOF-MS in this study has allowed structure elucidation of 186 MS/MS product ions previously selected for the LC/MS/MS analysis of 62 veterinary drugs. This serves to reduce the chances of false positives and negatives in the monitoring program, and provides justification and defense in regulatory enforcement actions.

Quantification of clenbuterol at trace level in human urine by ultra-high pressure liquid chromatography-tandem mass spectrometry

Clenbuterol is a β2 agonist agent with anabolic properties given by the increase in the muscular mass in parallel to the decrease of the body fat. For this reason, the use of clenbuterol is forbidden by the World Anti-Doping Agency (WADA) in the practice of sport. This compound is of particular interest for anti-doping authorities and WADA-accredited laboratories due to the recent reporting of risk of unintentional doping following the eating of meat contaminated with traces of clenbuterol in some countries. In this work, the development and the validation of an ultra-high pressure liquid chromatography coupled to electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) method for the quantification of clenbuterol in human urine is described. The analyte was extracted from urine samples by liquid-liquid extraction (LLE) in basic conditions using tert butyl-methyl ether (TBME) and analyzed by UHPLC-MS/MS with a linear gradient of acetonitrile in 9min only. The simple and rapid method presented here was validated in compliance with authority guidelines and showed a limit of quantification at 5pg/mL and a linearity range from 5pg/mL to 300pg/mL. Good trueness (85.8-105%), repeatability (5.7-10.6% RSD) and intermediate precision (5.9-14.9% RSD) results were obtained. The method was then applied to real samples from eighteen volunteers collecting urines after single oral doses administration (1, 5 and 10μg) of clenbuterol-enriched yogurts.

Development and validation of a ultra high performance liquid chromatography-tandem mass spectrometric method for the direct detection of formoterol in human urine

Formoterol is a long acting β(2)-agonist and has proven to be a very effective bronchodilating agent. Hence it is frequently applied therapeutically for the treatment of asthma. Because β(2)-agonists might be misused in sports for the stimulatory effects and for growth-promoting action their use is restricted. Since January 2012, formoterol is prohibited in urinary concentrations higher than 30 ng/mL. The objective of this study was to develop and validate a simple and robust ultra high performance liquid chromatographic-tandem mass spectrometric (UHPLC-MS/MS) method for the direct quantification of formoterol in urine. Sample preparation was limited to an enzymatic hydrolysis step after which 2 μL was injected in the chromatographic system. Chromatography was performed on a C(8)-column using gradient conditions. The mobile phase consisted of water/methanol (H(2)O/MeOH) both containing 0.1% acetic acid (HOAc) and 1mM ammonium acetate (NH(4)OAc). Calibration curve were constructed between 15 and 60 ng/mL. Validation data showed bias of 1.3% and imprecision of 5.4% at the threshold. Ion suppression/enhancement never exceeded 7%. Calculating measurement uncertainty showed proof of applicability of the method. Stability of formoterol was also investigated at 56 °C (accelerated stability test) at pH 1.0/5.2/7.0 and 9.5. At the physiological pH values of 5.2 and 7.0, formoterol showed good stability. At pH 1.0 and 9.5 significant degradation was observed.

Quantitative detection of inhaled formoterol in human urine and relevance to doping control analysis

Formoterol is a frequently prescribed β(2)-agonist used for the treatment of asthma. Due to performance-enhancing effects of some β(2) -agonists, formoterol appears on the prohibited list, published by the World Anti-doping Agency (WADA). Its therapeutic use is allowed but restricted to inhalation. Since the data on urinary concentrations originating from therapeutic use is limited, no discrimination can be made between use and misuse when a routine sample is found to contain formoterol. Therefore the urinary excretion of six volunteers after inhalation of 18 µg of formoterol was investigated. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of formoterol in urine samples. Sample preparation consists of an enzymatic hydrolysis of the urine samples, followed by a liquid-liquid extraction at pH 9.5 with diethyl ether/isopropanol (5/1, v/v). Analysis was performed using selected reaction monitoring after electrospray ionization. The method was linear in the range of 0.5-50 ng/ml. The limit of quantification (LOQ) was 0.5 ng/ml. The bias ranged between -1.0 and -6.8 %. Results for the urinary excretion show that formoterol could be detected for 72 h. The maximum urinary concentration detected was 8.5 ng/ml without and 11.4 ng/ml after enzymatic hydrolysis. Cumulative data showed that maximum 11.5% and 23% of the administered dose is excreted as parent drug within the first 12 h, respectively, non-conjugated and conjugated. Analysis of 82 routine doping samples, declared positive for formoterol during routine analysis, did not exhibit concentrations which could be attributed to misuse.

Development and validation of an open screening method for diuretics, stimulants and selected compounds in human urine by UHPLC-HRMS for doping control

A new doping control screening method for the analysis of diuretics and stimulants using ultra high pressure liquid chromatography-high resolution Orbitrap mass spectrometry has been developed. The screening was performed in full scan MS with scan-to-scan polarity switching which allowed to detect more than 120 target analytes. Sample preparation was limited to 10-fold dilution of the urine into the internal standard solution followed by injection. Total run time per sample was 10 min. Validation of the method yielded detection limits for diuretics between 25 and 250 ng mL(-1) and for stimulants between 5 and 500 ng mL(-1). The screening method has been implemented in routine doping control.

Quantitative detection of inhaled salmeterol in human urine and relevance to doping control analysis

Salmeterol is a frequently prescribed β₂-agonist used for the treatment of asthma. Due to performance-enhancing effects of some β₂-agonists, salmeterol appears on the prohibited list published by the World Anti-Doping Agency and its therapeutic use is allowed but restricted to inhalation. Because the data on urinary concentrations originating from therapeutic use are limited, no discrimination can be made between use and abuse when a routine sample is found to contain salmeterol. Therefore, the urinary excretion of 100 μg of inhaled salmeterol was investigated. A liquid chromatography-tandem mass spectrometry method was developed and validated for the quantification of urine samples. Sample preparation consists of an enzymatic hydrolysis of the urine samples followed by a liquid-liquid extraction at pH 9.5 with diethyl ether/isopropanol (5/1). Analysis was performed using selected reaction monitoring after electrospray ionization. The method was linear in the range of 0.5-50 ng/mL. The limits of quantification were 500 pg/mL. The inaccuracy ranged between 10.4% and -3.7%. Results show that salmeterol could be detected for 48 hours. The maximum urinary concentration detected was 1.27 ng/mL. Cumulative data showed that only 0.27% of the administered dose is excreted as parent drug within the first 12 hours. Analysis of 47 routine doping samples, declared to contain salmeterol during routine analysis, did not exhibit concentrations that could be considered originating from supratherapeutic doses.

Recent developments in MS for small molecules: application to human doping control analysis

Recent developments in MS for the detection of small molecules in the context of doping control analysis are reviewed. Doping control analysis is evolving together with MS, which is the technique of choice in order to accomplish the analytical requirements in this field. Since these analytical requirements for the detection of a doping agent depend on the substance, in the first section we review the different scenarios. The commonly established approaches, together with their achievements and drawbacks are described. New developments in hyphenated MS techniques (both GC–MS/MS and LC–MS/MS) concerning interfaces and analyzers are mentioned. The use (or potential use) of these developments in order to minimize the limitations of the commonly established approaches in the doping control field is discussed. Finally, a brief discussion about trends and remaining limitations is presented.

Analytical methods for the detection of clenbuterol

Clenbuterol is therapeutically used for the treatment of pulmonary diseases such as bronchial asthma or for tocolytic reasons. In cattle feeding as well as in sports it is illicitly misused due to its anabolic properties to promote muscle growth. Sample preparation procedures and analytical techniques used for the detection of clenbuterol are manifold and vary with the objectives of the investigation. Methods for its detection in biological specimens, drug preparations, the environment, food and feed products are reported. They are mainly based on immunochemical, chromatographic and mass spectrometric techniques, or on capillary electrophoresis. Sample preparation primarily includes liquid-liquid extraction and solid-phase extraction. Depending on the aim of the method clenbuterol can be determined in single- or multi-analyte methods. In biological and environmental samples concentrations are generally low due to the potency of the drug. Thus, highly sensitive procedures are required for expedient analyses.

Validated stability-indicating derivative and derivative ratio methods for the determination of some drugs used to alleviate respiratory tract disorders and their degradation products

Derivative and derivative ratio methods are presented for the determination of butamirate citrate, formoterol fumarate, montelukast sodium, and sodium cromoglycate. Using the second derivative ultraviolet (UV) spectrophotometry, butamirate citrate and formoterol fumarate were determined by measuring the peak amplitude at 260.4 and 261.8 nm, respectively, without any interference of their degradation products. Butamirate citrate degradation product, 2-phenyl butyric acid, was determined by the measurement of its second derivative amplitude at 246.7 nm where butamirate citrate displays zero crossing. Formoterol fumarate degradation product, desformyl derivative, could be evaluated through the use of the first derivative at peak amplitude of 264.8 nm where interference of formoterol fumarate is negligible. In the first mode, the zero-crossing technique was applied at 305 nm for the determination of montelukast sodium in the presence of its photodegradation product, cis-isomer. The derivative of ratio spectra of montelukast sodium and its cis- isomer were used to determine both isomers using the first derivative of the ratio spectra by measuring the amplitudes of the trough at 305 nm and the peak at 308 nm, respectively. The later technique was also used for the determination of a ternary mixture of sodium cromoglycate and its two degradation products using zero-crossing method. In the derivative ratio spectra of the ternary mixture, trough depths were measured at 271.6, 302.8 and 302.2 nm, using the second, the first, and the second mode to evaluate sodium cromoglycate, degradation product (1) and degradation product (2), respectively. All the methods were applied successfully to the pharmaceutical preparation and were validated according to ICH guidelines.

Simultaneous determination of beta2-agonists in human urine by fast-gas chromatography/mass spectrometry: method validation and clinical application

A fast screening protocol was developed and validated for the simultaneous determination of 15 beta(2)-agonists in human urine (bambuterol, cimbuterol, clenbuterol, fenoterol, formoterol, isoproterenol, mapenterol, metaproterenol, procaterol, ractopamine, ritodrine, salbutamol, salmeterol, terbutaline, tulobuterol). The overall sample processing includes deconjugation with enzyme hydrolysis, liquid-liquid extraction, followed by derivatization of the extract and detection of beta(2)-agonists trimethylsilyl-derivatives by fast-gas chromatography/electron impact-mass spectrometry (fast-GC/EI-MS). Sample extraction and derivatization were optimized with the purpose of improving recoveries and reaction yields for a variety of analytes with different structures simultaneously, while keeping the procedure simple and reliable. Validation parameters were determined for each analyte under investigation, including selectivity, linearity, intra- and inter-assay precision, extraction recoveries and signal to noise ratio (S/N) at the lowest calibration level. Fast-GC/MS sequences, based on the use of short columns, high carrier-gas velocity and fast temperature ramping, allow considerable reduction of the analysis time (7 min), while maintaining adequate chromatographic resolution. The overall GC cycle time was less than 9 min, allowing a processing rate of 6 samples/h. High MS-sampling rate, using a benchtop quadrupole mass analyzer, resulted in accurate peak shape definition under both scan and selected ion monitoring modes, and high sensitivity in the latter mode. The method was successfully tested on real samples arising from clinical treatments. Copyright (c) 2009 John Wiley & Sons, Ltd.

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.

Quantitative determination of fenoterol and fenoterol derivatives in rat plasma using on-line immunoextraction and liquid chromatography/mass spectrometry

An on-line immunoextraction and liquid chromatography/mass spectrometry (LC/MS) method was developed and validated for the determination of R,R'-fenoterol, R,R'-methoxyfenoterol and R,S'-naphthylfenoterol in rat plasma. Sample preparation involved immunoextraction of analytes using an antibody raised against R,R'- and R,S'-aminofenoterol that was immobilized onto chromatographic support. LC was performed on a Waters hydrophilic interaction chromatography (HILIC) column (150 mm x 2.1mm), using an isocratic mobile phase of methanol:ammonium acetate (10mM, pH 6.8) (90:10, v/v) at a flow rate of 0.2 ml/min. The MS was operated in the single ion monitoring mode (m/z 304.2 for R,R'-fenoterol, m/z 318.1 for R,R'-methoxyfenoterol, and m/z 339.2 for R,S'-naphthylfenoterol). Optimization of analytes desorption process from the immunoextraction column was performed by factorial analysis and the sample calibration curves were made with spiked rat plasma samples containing 0.5-100 ng/ml of drugs. The cross-selectivity studies of the antibody were determined and the results suggested high selectivities toward R,R'-fenoterol, R,R'-methoxyfenoterol and R,S'-naphthylfenoterol. The accuracy of assay was more than 96% while intra- and inter-day precision of assay were less than 12.4%. Stability studies (2h benchtop, freeze/thaw, and autosampler stability) were conducted and the analytes were stable through out studies. The validated method was used to determine the plasma concentration-time profiles of drugs after oral administration to rats of R,R'-fenoterol, R,R'-methoxyfenoterol and R,S'-naphthylfenoterol.

The analytical chemistry of drug monitoring in athletes

The detection and deterrence of the abuse of performance-enhancing drugs in sport are important to maintaining a level playing field among athletes and to decreasing the risk to athletes' health. The World Anti-Doping Program consists of six documents, three of which play a role in analytical development: The World Anti-Doping Code, The List of Prohibited Substances and Methods, and The International Standard for Laboratories. Among the classes of prohibited substances, three have given rise to the most recent analytical developments in the field: anabolic agents; peptide and protein hormones; and methods to increase oxygen delivery to the tissues, including recombinant erythropoietin. Methods for anabolic agents, including designer steroids, have been enhanced through the use of liquid chromatography/tandem mass spectrometry and gas chromatography/combustion/isotope-ratio mass spectrometry. Protein and peptide identification and quantification have benefited from advances in liquid chromatography/tandem mass spectrometry. Incorporation of techniques such as flow cytometry and isoelectric focusing have supported the detection of blood doping.

Structural evaluation of the glucuronides of morphine and formoterol using chemical derivatization with 1,2-dimethylimidazole-4-sulfonyl chloride and liquid chromatography/ion trap mass spectrometry

For the first time chemical derivatization of isomeric drug glucuronides with 1,2-dimethylimidazole-4-sulfonyl chloride (DMISC) has been successfully applied as a tool for determining the site of conjugation. This provides a way to differentiate between glucuronide isomers containing aliphatic and phenolic hydroxyl groups. The analyses were performed with liquid chromatography/electrospray ion trap mass spectrometry (LC/ESI-MSn). DMISC has previously been shown to react selectively with phenols in estrogens, thus improving sensitivity in ESI-MS. The model compounds selected for this study were commercially available standards of formoterol, morphine, morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G). Formoterol glucuronides were produced with an enzymatic method in house. Both formoterol and morphine possess one phenolic and one aliphatic hydroxyl group where glucuronidation could take place. The product ion mass spectra of the native morphine glucuronides were indistinguishable due to the initial neutral loss of monodehydrated glucuronic acid (176 u). However, a significant difference between the isomers was observed with DMISC derivatization, as only the form with a free phenol, M6G, gave a detectable reaction product. Formoterol formed two detectable glucuronide isomers in the enzymatic reaction. Their respective sites of conjugation could not be directly determined from the product ion spectra. Reaction with DMISC, however, gave a detectable product with only one of the isomers. Based on previous experience of the preferred DMISC reactions with phenols, and interpretation of the fragmentation pattern of the derivative, it was concluded that the reactive isomer had a free phenol, and was thus conjugated on the aliphatic chain.