Preventive doping control screening analysis of prohibited substances in human urine using rapid‐resolution liquid chromatography/high‐resolution time‐of‐flight mass spectrometry

Unification of the screening protocols for a wide range of doping agents has become an important issue for doping control laboratories. This study presents the development and validation of a generic liquid chromatography/time‐of‐flight mass spectrometry (LC/TOFMS) screening method of 241 small molecule analytes from various categories of prohibited substances (stimulants, narcotics, diuretics, β₂‐agonists, β‐blockers, hormone antagonists and modulators, glucocorticosteroids and anabolic agents). It is based on a single‐step liquid‐liquid extraction of hydrolyzed urine and the use of a rapid‐resolution liquid chromatography/high‐resolution time‐of‐flight mass spectrometric system acquiring continuous full scan data. Electrospray ionization in the positive mode was used. Validation parameters consisted of identification capability, limit of detection, specificity, ion suppression, extraction recovery, repeatability and mass accuracy. Detection criteria were established on the basis of retention time reproducibility and mass accuracy. The suitability of the methodology for doping control was demonstrated with positive urine samples. The preventive role of the method was proved by the case where full scan acquisition with accurate mass measurement allowed the retrospective reprocessing of acquired data from past doping control samples for the detection of a designer drug, the stimulant 4‐methyl‐2‐hexanamine, which resulted in re‐reporting a number of stored samples as positives for this particular substance, when, initially, they had been reported as negatives. Copyright © 2010 John Wiley & Sons, Ltd.     

Doping control analysis of desmopressin in human urine by LC‐ESI‐MS/MS after urine delipidation

The World Anti‐Doping Agency (WADA) has recently added desmopressin, a synthetic analogue of the endogenous peptide hormone arginine vasopressin, to the Prohibited List, owing to the potential masking effects of this drug on hematic parameters useful to detect blood doping. A qualitative method for detection of desmopressin in human urine by high‐performance liquid chromatography–electrospray tandem mass spectrometry (LC‐ESI‐MS/MS) has been developed and validated. Desmopressin purification from urine was achieved by means of delipidation with a 60:40 di‐isopropyl ether/n‐butanol and solid‐phase extraction with WCX cartridges. The lower limit of detection was 25 pg/mL. Extraction recovery was determined as 59.3% (SD 29.4), and signal reduction owing to ion suppression was estimated to be 42.7% (SD 12.9). The applicability of the method was proven by the analysis of real urine samples obtained after intravenous, oral and intranasal administration of desmopressin, achieving unambiguous detection of the peptide in all the cases. Copyright © 2012 John Wiley & Sons, Ltd.     

Simultaneous determination of six toxic alkaloids in human plasma and urine using capillary zone electrophoresis coupled to time‐of‐flight mass spectrometry

A novel capillary zone electrophoresis separation coupled to electro spray ionization time‐of‐flight mass spectrometry method was developed for the simultaneous analysis of six toxic alkaloids: brucine, strychnine, atropine sulfate, anisodamine hydrobromide, scopolamine hydrobromide and anisodine hydrobromide in human plasma and urine. To obtain optimal sensitivity, a solid‐phase extraction method using Oasis MCX cartridges (1 mL, 30 mg; Waters, USA) for the pretreatment of samples was used. All compounds were separated by capillary zone electrophoresis at 25 kV within 12 min in an uncoated fused‐silica capillary of 75 μm id × 100 cm and were detected by time‐of‐flight mass spectrometry. This method was validated with regard to precision, accuracy, sensitivity, linear range, limit of detection (LOD), and limit of quantification (LOQ). In the plasma and urine samples, the linear calibration curves were obtained over the range of 0.50–100 ng/mL. The LOD and LOQ were 0.2–0.5 ng/mL and 0.5–1.0 ng/mL, respectively. The intra‐ and interday precision was better than 12% and 13%, respectively. Electrophoretic peaks could be identified by mass analysis.     

Magnetic separation as a new method for the extraction of small molecules from biological fluids of humans

A new version of extraction is proposed for the extraction of doping substances from urine. It is based on magnetic separation using ferromagnetic microparticles with the surface modified with C₁₈ groups. A procedure is developed on its basis for the quantification of selective modulators of androgen receptors and peroxisome proliferator-activated delta-receptor agonists using high-performance liquid chromatography coupled with tandem mass spectrometry. Using the proposed approach, the recovery of doping substances from human biological fluids approximates 100%, while the negative effect of the matrix components on the ionization of target compounds is reduced to a minimum. In contrast to solid phase extraction and liquid-liquid extraction, the method of magnetic separation appears to be more rapid and simple. The time of pretreatment for a sample intended for HPLC coupled to tandem mass spectrometry makes 5 min; the detection limit makes 0.25–5 ng/mL.     

A comprehensive library‐based,automated screening procedure for 46 synthetic cannabinoids in serum employing liquid chromatography‐quadrupole ion trap mass spectrometry with high‐temperature electrospray ionization

Considering the vast variety of synthetic cannabinoids and herbal mixtures – commonly known as ‘Spice’ or ‘K2’ – on the market and the resulting increase of severe intoxications related to their consumption, there is a need in clinical and forensic toxicology for comprehensive up‐to‐date screening methods. The focus of this project aimed at developing and implementing an automated screening procedure for the detection of synthetic cannabinoids in serum using a liquid chromatography‐ion trap‐MS (LC‐MSⁿ) system and a spectra library‐based approach, currently including 46 synthetic cannabinoids and 8 isotope labelled analogues. In the process of method development, a high‐temperature ESI source (IonBooster^TM, Bruker Daltonik) and its effects on the ionization efficiency of the investigated synthetic cannabinoids were evaluated and compared to a conventional ESI source. Despite their structural diversity, all investigated synthetic cannabinoids benefitted from high‐temperature ionization by showing remarkably higher MS intensities compared to conventional ESI. The employed search algorithm matches retention time, MS and MS²/MS³ spectra. With the utilization of the ionBooster source, limits for the automated detection comparable to cut‐off values of routine MRM methods were achieved for the majority of analytes. Even compounds not identified when using a conventional ESI source were detected using the ionBooster‐source. LODs in serum range from 0.1 ng/ml to 0.5 ng/ml. The use of parent compounds as analytical targets offers the possibility of instantly adding new emerging compounds to the library and immediately applying the updated method to serum samples, allowing the rapid adaptation of the screening method to ongoing forensic or clinical requirements. The presented approach can also be applied to other specimens, such as oral fluid or hair, and herbal mixtures and was successfully applied to authentic serum samples. Quantitative MRM results of samples with analyte concentrations above the determined LOD were confirmed as positive findings by the presented method. Copyright © 2014 John Wiley & Sons, Ltd.     

Rapid determination of rifaximin on dried blood spots by LC‐ESI‐MS

The use of blood spot collection cards is a simple way to obtain specimens for therapeutic drug monitoring, assessing adherence to medications and preventing toxicity in a clinical setting. A high‐throughput liquid chromatography–electrospray ionization mass spectrometric (LC‐ESI‐MS) method for determination of rifaximin on dried blood spots (DBS) was developed and validated. It involves solvent extraction of a punch of DBS followed by reversed‐phase LC on a monolithic column consisting of a silica rod with bimodal pore structure and detection by ESI‐MS. Rifampicin was used as an internal standard (IS). The run time was within 5.0 min with a very low back‐pressure at a flow rate of 0.5 mL/min. The assay was linear from 0.1 to 10 ng/mL. The mean recovery was 98.42%. The developed method is very simple, rapid and useful for clinical applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Determination of hormones in human urine by ultra‐high‐performance liquid chromatography/triple‐quadrupole mass spectrometry

Steroid hormones play a critical role in maintaining the homeostasis of human metabolism. Urine as a noninvasive sample has been extensively used in clinical diagnosis for hormones homeostasis. In this study, the simultaneous characterization of fourteen hormones in urine was performed based on ultra‐high‐performance liquid chromatography/electrospray ionization tandem mass spectrometry (UPHLC/ESI(+)‐MS/MS) with multiple reaction monitoring in the positive ionization mode. The target hormones were cortisone, cortisol, 11‐deoxycortisol, aldosterone, corticosterone, 11‐deoxycorticosterone, progesterone, 17‐OH‐progesterone, pregnenolone, estrone, estradiol, estriol, testosterone and dehydreopiandrosterone. β‐Glucuronidase/sulfatase deconjugation and liquid–liquid extraction (LLE) were conducted for the determination of urinary hormones (free + conjugated forms). The limits of detection (LODs) ranged from 0.2 ng/mL (11‐deoxycortisol and testosterone) to 1 ng/mL (cortisone). The extraction recovery of the targeted compounds ranged from 87% to 127%, indicating sufficient extraction efficiency for the LLE process. Intraday precision was below 10% and the accuracy ranged from 84% to 122%. The profiling analysis of hormones in urine samples helps to understand the metabolic state of biological systems and can be employed as a diagnostic tool in diseases developed by endocrine‐disrupted systems.     

Screening of methylenedioxyamphetamine‐ and piperazine‐derived designer drugs in urine by LC–MS/MS using neutral loss and precursor ion scan

This study describes a method for the screening of methylenedioxyamphetamine‐ and piperazine‐derived compounds in urine by liquid chromatography‐tandem mass spectrometry. These substances, characterized by possessing common moieties, are screened using precursor ion and neutral loss scan mode and then quantified in multiple reaction monitoring acquisition mode. Based on the product‐ion spectra of different known molecules, chosen as ‘model’, characteristic neutral losses and product ions were selected: piperazines were detected in precursor ion scan of m/z 44 and neutral loss of 43 and 86 while amphetamines in precursor ion scan of m/z 133, 135 and 163. The applicability of the screening approach was studied in blank urine spiked with selected analytes and processed by solid‐phase extraction. Linearity, matrix effect, precision, accuracy, limits of detection and limits of quantification were evaluated both for the screening and the quantification methods. The ability of the screening method to provide semi‐quantitative data was demonstrated. This method appears to be a useful tool for the identification of designer drugs derived from piperazines or methylenedioxyamphetamines and can be potentially applied to other drug classes. Copyright © 2013 John Wiley & Sons, Ltd.     

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

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

Ultrasound‐assisted dispersive micro‐solid‐phase extraction based on N‐doped mesoporous carbon and high‐performance liquid chromatographic determination of 1‐hydroxypyrene in urine samples

In this research, a new ultrasound‐assisted dispersive micro‐solid‐phase extraction method based on N‐doped mesoporous carbon sorbent followed by high‐performance liquid chromatography equipped with diode array detector for trace measurement of 1‐hydroxypyrene as a metabolite of exposure to polycyclic aromatic hydrocarbons was optimized. Herein, the hard template method was used for the preparation of N‐doped mesoporous carbon sorbent. The prepared sorbent was characterized using the Brunauer–Emmett–Teller method, transmission electron microscopy, and elemental analysis. Parameters affecting the extraction of the target metabolite were investigated using the Box–Behnken design method. Considering optimum parameters, the plotted calibration curve for 1‐hydroxypyrene was linearly correlated with the concentration span of 0.1–50 μg/L for urine media. The accuracy of the optimized procedure was examined through the relative recovery tests on the fortified urine specimens. The relative recoveries fell between 95 and 101%. The method detection limit of the proposed procedure was also calculated to be 0.03 μg/L.     

Identification of metabolites of Danggui Buxue Tang in rat urine by liquid chromatography coupled with electrospray ionization time‐of‐flight mass spectrometry

A method coupling liquid chromatography with electrospray ionization time‐of‐flight mass spectrometry (LC/ESI‐TOF/MS) has been developed for rapid and sensitive analysis of rat urinary metabolite profile of Danggui Buxue Tang (DBT), a well‐known Chinese herbal formula. After oral administration of DBT, urine samples were collected during 0–24 h, and then pretreated by solid‐phase extraction. A total of 68 compounds including 13 parent compounds and 55 metabolites were detected in the drug‐containing urines compared with blank urines. The total analytical time was less than 20 min. Metabolites of DBT were identified using dynamic adjustment of the fragmentor voltage to produce structure‐relevant fragment ions. By using this approach, the mass accuracy of precursor and fragment ions was typically within ±5 ppm of the theoretical values, and enabled the identification of 43 metabolites including 27 isoflavanoid and 16 phthalide metabolites. Our results indicated that glucuronidation and sulfation were the major metabolic pathways of isoflavonoids, while glutathione conjugation, glucuronidation and sulfation were the main metabolic pathways of phthalides. No saponin‐related metabolites were detected. The results of the present study provided important structural information relating to the metabolism of DBT. Furthermore, this work demonstrated the potential of the LC/ESI‐TOF/MS approach for identification of metabolites from Chinese herbal medicines in urine. Copyright © 2009 John Wiley & Sons, Ltd.     

Direct determination of pregabalin in human urine by nonaqueous CE‐TOF‐MS

Determination of pregabalin in urine samples was carried out by nonaqueous CE with TOF‐MS via ESI, with a mixture of 10 mM ammonium formate and 0.05% acetic acid in methanol. By using TOF‐MS, accurate mass information was obtained, thus causing a great improvement in qualitative ability. In order to avoid ionic suppression, urine samples dilution 1:10 was used. This was the only treatment to urine samples before the injection. Despite this dilution, the detection limit was as low as 0.03 μg/mL for pregabalin. The method was validated with respect to accuracy, precision, and linearity, LOD, and LOQ. This method was applied to the analysis of urine samples from seven different cancer patients undergoing treatment with pregabalin. The developed method may find wide application for the routine determination of pregabalin in biological samples in order to establish a more efficient and safe dosage.     

Dispersive solid‐phase extraction procedure coupled to UPLC‐ESI‐MS/MS analysis for the simultaneous determination of thirteen cytotoxic drugs in human urine

A fast and easy tailored dispersive solid‐phase extraction (d‐SPE) procedure has been developed for the determination of 13 cytostatic drugs. Combined with a rapid and simultaneous ultra performance liquid chromatography/tandem mass spectrometry method for residue identification and quantification in urine, it has been fully validated and tested to study a realistic situation in working environment. The target compounds were chosen from the most common classes used in hospitals. The d‐SPE adsorbent was obtained mixing Oasis HLB® with C₁₈ and applied to a large volume of sample (10 mL). The electrospray ionization‐mass spectrometry acquisition was conducted in a mixed period mode: six acquisition windows were in positive ionization and one in negative (for 5‐fluorouracil). The lowest limit of quantification was found at 0.04 μg/L urine for methotrexate. The absolute recovery of cytotoxic drugs was assessed at two concentrations levels and ranged from 67.1% (cytarabine) to 102.3% (etoposide) and from 65.3% (cytarabine) to 101.2% (methotrexate) for the lower and higher levels, respectively, with the relative standard deviation always <12%. This method gives the opportunity to analyze drugs in a wide molecular weight range (from 130 to 853 a.m.u.) and in a complex matrix, such as urine, without losing any of the features that a method intended for trace quantification must have. Copyright © 2016 John Wiley & Sons, Ltd.     

Simultaneous analysis of fourteen tertiary amine stimulants in human urine for doping control purposes by liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry

A method for the simultaneous screening and confirmation of the presence of fourteen tertiary amine stimulants in human urine by gas chromatography-mass spectrometry (GC-MS) in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed and validated. Solid phase extraction (SPE) and liquid-liquid extraction (LLE) approaches were utilized for the pre-treatment of the urine samples. The study indicated that the capillary temperature played a significant role in the signal abundances of the protonated molecules of cropropamide and crotethamide under positive ion electrospray ionization (ESI) conditions. In addition, comparison studies of two different pre-treatment approaches as well as the two ionization modes were conducted. The LODs of the developed method for all the analytes were lower than the minimum required performance limit (MRPL) as set forth in the World Anti-Doping Agency (WADA) technical document for laboratories. The human urine sample obtained after oral administration of prolintane·HCl was successfully analyzed by the developed method, which demonstrated the applicability and reliability of the method for routine doping control analysis.     

Determination of urinary 8‐hydroxy‐2′‐deoxyguanosine by a combination of on‐line molecularly imprinted monolithic solid phase microextraction with high performance liquid chromatography–ultraviolet detection

8‐Hydroxy‐2′‐deoxyguanosine (8‐OHdG) is a sensitive biomarker for DNA oxidative damage. However, its determination in human urine is confounded by trace level and complex matrix. In this study, a new configuration of on‐line solid phase microextraction coupled to high performance liquid chromatography‐ultraviolet detection was established with molecularly imprinted monolithic column as extraction sorbent. The tailor made monolith exhibited high extraction efficiency with the enrichment factor 101.84 for 8‐OHdG owing to its special porous structure and inherent selectivity. Under optimal condition, appreciable sensitivity had been achieved for this incorporation with limit of detection 2.04 nmol/L (S/N = 3) and limit of quantification 7.12 nmol/L (S/N = 10), respectively. Precise determination with wide range linearity (0.007–5.00 μmol/L) afforded a practical alternative in urinary 8‐OHdG analysis and 107 different subjects had been successfully analyzed. This newly developed method embodied useful prospect for the investigation of DNA oxidative damage with less expense, convenient maintenance and ease of operation     

Identification of the absorptive constituents and their metabolites in vivo of Puerariae Lobatae Radix decoction orally administered in WZS‐miniature pigs by HPLC‐ESI‐Q‐TOFMS

In this study, the technique of high‐performance liquid chromatography coupled with electrospray ionization quadrupole time‐of‐flight mass spectrometry (HPLC‐ESI‐Q‐TOFMS) was used to analyze and identify the absorptive constituents and their metabolites in drug‐containing urine of Wuzhishan (WZS)‐miniature pigs administered with Puerariae Lobatae Radix (PLR) decoction. With the accurate mass measurements (<5 ppm) and effective MS² fragment ions, 96 compounds, including eight original constituents and 88 metabolites, were identified from the drug‐containing urine. Among these, 64 metabolites were new ones and their structures can be categorized into five types: isoflavones, puerols, O‐desmethylangolensins, equols and isoflavanones. In particular, puerol‐type constituents in PLR were first proved to be absorptive in vivo. Meanwhile, the metabolic pathways of PLR in vivo were investigated. On the basis of relative content of the identified compounds, 13 major metabolites accounting for approximately 50% of the contents, as well as their corresponding 12 prototype compounds, were determined as the major original absorptive constituents and metabolites of PLR in vivo. The HPLC‐ESI‐Q‐TOFMS technique proved to be powerful for characterizing the chemical constituents from the complicated traditional Chinese medicine matrices in this research. Copyright © 2013 John Wiley & Sons, Ltd.     

High‐throughput polymer tip‐electrospray ionization mass spectrometry for enhanced detection of neopterin and biopterin in clinical urine samples

Urinary biopterin (Bio) and neopterin (Neo) are important markers for clinical diagnosis of hyperphenylalaninemia. Herein, we developed a high‐throughput analysis method based on electrospray ionization mass spectrometry (ESI‐MS) with polymer tips for the rapid quantitative detection of Bio and Neo in clinical urine samples. Different polymer tips were investigated. It is found that the best detection sensitivity was achieved with hydrophobic polymer tip, ie, polyethylene tips. The high‐throughput polymer tip‐ESI‐MS method allowed a rapid analysis speed at ~40 seconds per sample. The limits of quantification (LOQ) (S/N ≥ 10) for the detection of Bio and Neo were improved to be 5.0 ng/mL. Acceptable relative standard deviation (RSD) values for Neo and Bio were measured to be 12.2% and 13.4% for direct measurement of Bio and Neo in raw urine samples, respectively. Furthermore, Bio and Neo were directly quantified from 18 clinical urine samples by presented method. The ratios of urinary Bio‐to‐Neo were analyzed for diagnosis of hyperphenylalaninemia. The results demonstrated that the present polymer tip‐ESI‐MS method is a promising strategy for the rapid analysis of clinical samples.     

Validation and application of a screening method for beta2-agonists, anti-estrogenic substances and mesocarb in human urine using liquid chromatography/tandem mass spectrometry

Electrospray ionization (ESI) mass spectra of 15 anti-estrogenic substances, beta2-agonists and mesocarb were investigated in terms of fragmentation patterns. On the basis of this product ion information, a simultaneous screening method for anti-estrogenic substances, beta2-agonists and mesocarb was developed for doping control purposes. After hydrolysis, liquid-liquid extraction was adopted for the sample preparation. The recoveries for all compounds were 30 and 96%. A single liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis could be performed in 13 min for the analysis of 15 anti-estrogenic substances, beta2-agonists and mesocarb. A quantitative analysis was also validated. Inaccuracies were below +/-12% and precisions varied from 0 to 15.8%. The limit of detection was below 10 ng/mL except formestane (300 ng/mL) and aminoglutethimide (100 ng/mL). The validated method was applied for the analysis of excretion samples.     

Magnetic porous carbon derived from a metal–organic framework as a magnetic solid‐phase extraction adsorbent for the extraction of sex hormones from water and human urine

An iron‐embedded porous carbon material (MIL‐53‐C) was fabricated by the direct carbonization of MIL‐53. The MIL‐53‐C possesses a high surface area and good magnetic behavior. The structure, morphology, magnetic property, and porosity of the MIL‐53‐C were studied by scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, and N₂ adsorption. With the use of MIL‐53‐C as the magnetic solid‐phase extraction adsorbent, a simple and efficient method was developed for the magnetic solid‐phase extraction of three hormones from water and human urine samples before high‐performance liquid chromatography with UV detection. The developed method exhibits a good linear response in the range of 0.02–100 ng/mL for water and 0.5–100 ng/mL for human urine samples , respectively. The limit of detection (S/N = 3) for the analytes was 0.005–0.01 ng/mL for water sample and 0.1–0.3 ng/mL for human urine sample. The limit of quantification (S/N = 10) of the analytes were in the range of 0.015–0.030 and 0.3–0.9 ng/mL, respectively.