Journal of Chromatography B (v.879, #15-16)

We developed and validated a quantitative method for simultaneously determining the concentrations of tracheloside and trachelogenin in rat plasma. Plasma samples were prepared by liquid–liquid extraction with ethyl acetate. Isocratic chromatographic separation was performed on a reversed-phase Diamonsil C18 column (4.6 × 200 mm, 5 μm). The mobile phase consisted of methanol and 10 mM aqueous ammonium formate (80:20, v/v). Analyte detection was achieved by positive electrospray ionization (ESI) tandem mass spectrometry. Calibration was performed by internal standardization with glipizide, and regression curves ranging from 0.625 to 625 ng/mL were constructed for both the analytes. The intra- and inter-day precision values were below 8%, and accuracy ranged from −5.33% to 2.53% in all quality control samples. In this study, the validated method was successfully applied to determine the pharmacokinetic profile of tracheloside and trachelogenin in rat plasma after oral and intravenous administration of trachelospermi total lignans.
Keywords: Lignan; Tracheloside; Trachelogenin; Tandem mass spectrometry; Quantification; Pharmacokinetics;

Simultaneous determination of eight β-lactam antibiotics in human serum by liquid chromatography–tandem mass spectrometry by Tomofumi Ohmori; Akio Suzuki; Takashi Niwa; Hiroaki Ushikoshi; Kunihiro Shirai; Shozo Yoshida; Shinji Ogura; Yoshinori Itoh (1038-1042).
A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the simultaneous determination of eight β-lactam antibiotics, including ampicillin, cefazolin, cefepime, cefmetazole, cefotaxime, doripenem, meropenem, and piperacillin, in human serum. Sample specimens were subjected to solid phase extraction (SPE) using Waters Oasis® HLB cartridges (30 mg). Chromatographic separation was performed with a high-resolution octadecyl silica column compatible with hydrophilic compounds, using a gradient of 10 mM aqueous ammonium formate containing 0.1% formic acid-methanol. Antibiotics were detected by a triple quadrupole mass spectrometer (MS/MS) with electrospray ionization and quantified by the multiple reaction monitoring mode. A total run time of 13 min was applied. Linearity in the calibration was obtained over a range of 0.1–50 μg/mL of the β-lactam antibiotics, except for doripenem. The lower limit of quantification was 0.005–0.5 μg/mL, using 50 μL serum. The recovery rate exceeded 80.2% for these analytes, except for doripenem (49.1%) and meropenem (62.3%). The present method is applicable to routine therapeutic monitoring of β-lactam antibiotics in clinical practice.
Keywords: β-lactam antibiotics; Liquid chromatography; Tandem mass spectrometry; Solid phase extraction;

A novel matrix derivatized from hydrophilic gigaporous polystyrene-based microspheres for high-speed immobilized-metal affinity chromatography by Jian-Bo Qu; Yong-Dong Huang; Guang-Lun Jing; Jian-Guo Liu; Wei-Qing Zhou; Hu Zhu; Jian-Ren Lu (1043-1048).
Agarose coated gigaporous polystyrene microspheres were evaluated as a novel matrix for immobilized-metal affinity chromatography (IMAC). With four steps, nickel ions were successfully immobilized on the microspheres. The gigaporous structure and chromatographic properties of IMAC medium were characterized. A column packed with the matrix showed low column backpressure and high column efficiency at high flow velocity. Furthermore, this matrix was used for purifying superoxide dismutase (SOD), which was expressed in Escherichia coli (E. coli) in submerged fermentation, on an Äkta purifier 100 system under different flow velocities. The purity of the SOD from this one-step purification was 79% and the recovery yield was about 89.6% under the superficial flow velocity of 3251 cm/h. In conclusion, all the results suggested that the gigaporous matrix has considerable advantages for high-speed immobilized-metal affinity chromatography.
Keywords: Gigaporous; Polystyrene microspheres; Column efficiency; Immobilized-metal affinity chromatography; Superoxide dismutase;

Mitragyna speciosa (Kratom in Thai), native in Southeast Asia, is increasingly misused as a herbal drug of abuse. During metabolism studies on the Kratom alkaloids mitragynine, its diastereomers speciogynine and speciociliatine as well as paynantheine in rats and humans, further isomeric compounds were detected in Kratom users’ urine. The question arose whether these compounds were formed from the low abundant, isomeric alkaloids mitraciliatine (MC) and isopaynantheine (ISO-PAY). Therefore, the aim of the presented study was to identify using liquid chromatography–linear ion trap-mass spectrometry their phase I and II metabolites in rat urine after administration of pure MC or ISO-PAY, to confirm their formation in humans, and finally to confirm whether the above-mentioned isomeric compounds in human urine represent MC and ISO-PAY and/or their metabolites. The metabolic pathways of both alkaloids in rats were found to be comparable to those of their corresponding diastereomers. In the human urines tested, not all metabolites found in rats could be detected because of the much lower amounts of MC and ISO-PAY in Kratom. However, all the above-mentioned so far unknown isomeric compounds could be identified in the human urine samples as MC, ISO-PAY and/or their metabolites. The used LC separation was also suitable for the differentiation of all other Kratom alkaloids and their metabolites in human urine.
Keywords: Kratom; Mitraciliatine; Isopaynantheine; Metabolism; LC–MS n ; Urine;

Coumadin (R/S-warfarin) is a commonly prescribed anticoagulant for over ∼20 million Americans. Although highly efficacious, positive clinical outcomes during warfarin therapy depend on maintaining a narrow therapeutic range for the drug. This goal is challenging due to large inter-individual variability in patient response, which has been attributed to diversity in drug metabolism. Warfarin is given as a racemic mixture and evidence suggest differences of R and S-warfarin in their therapeutic activities and metabolism. Previous investigation of warfarin metabolism has been hampered by the inability to quantify the individual enantiomers. To overcome this limitation a multi-mode LC–MS/MS method is reported. This strategy combines phenyl based reverse phase chromatography with chiral phase chromatography prior to quantitation by liquid chromatography tandem mass spectrometry. This approach was made possible through advances in UPLC technology producing narrow peaks suitable for transferring to a second column. The reported method separated individual R and S enantiomers of hydroxywarfarin and warfarin. All four possible isomers of 10-hydroxywarfarin were resolved to reveal unprecedented insights into the stereo-specific metabolism of warfarin. Characterization of the method demonstrated that it is robust and sensitive with inter-day coefficients of error between <7% and a detection limit of 2 nM in sample or 10 fmol on column for each analyte. Individual metabolites may be suitable surrogate biomarkers or predictive markers that predict warfarin dose, adverse interactions, or other important clinical outcomes during anticoagulant therapy. Consequently, the metabolite profiles obtained through this dual phase UPLC–MS/MS method are expected to increase our understanding of the role warfarin metabolism plays in patient response to therapy and yield new strategies to improve patient outcomes.
Keywords: Chiral; In-series; LC–MS/MS; Metabolic profiling; Warfarin;

Determination of moxifloxacin in dried blood spots using LC–MS/MS and the impact of the hematocrit and blood volume by D.H. Vu; R.A. Koster; J.W.C. Alffenaar; J.R.B.J. Brouwers; D.R.A. Uges (1063-1070).
Moxifloxacin (MFX) is a potential oral agent use in the treatment of multidrug-resistance tuberculosis (MDR-TB). Due to variability in pharmacokinetics and in vitro susceptibility of causative bacteria, therapeutic drug monitoring (TDM) of MFX is recommended. Conventional plasma sampling for TDM is facing logistical challenges, especially in limited resource areas, and dried blood spots (DBS) sampling may offer a chance to overcome this problem. The objective of this study was to develop a LC–MS/MS method for determination of MFX in dried blood spots (DBS) that is applicable for TDM. The influence of paper type, the hematocrit (Hct) and the blood volume per spot (V b) on the estimated blood volume in a disc (V est) was investigated. The extracts of 8 mm diameter discs punched out from DBS were analyzed using liquid chromatography tandem mass spectrometry (LC–MS/MS) with cyanoimipramin as internal standard. The method was validated with respect to selectivity, linearity, accuracy, precision, sensitivity, recovery and stability. The effect of Hct and V b on LC–MS/MS analytical result was also investigated. The relationship between MFX concentrations in venous and finger prick DBS and those in plasma was clinically explored. V est was highly influenced by Hct while the effect of V b appeared to be different among paper types. Calibration curves were linear in the range of 0.05–6.00 mg/L with inter-day and intra-day precisions and biases of less than 11.1%. The recovery was 84.5, 85.1 and 92.6% in response to blood concentration of 0.15, 2.50 and 5.00 mg/L, respectively. A matrix effect of less than 11.9% was observed. MFX in DBS was stable for at least 4 weeks at room condition (temperature of 25 °C and humidity of 50%). A large range of Hct value produced a significant analytical bias and it can be corrected with resulting DBS size. A good correlation between DBS and plasma concentrations was observed and comparable results between venous DBS and finger prick DBS was attained. This fully validated method is suitable for determination of MFX in dried blood spot and applicable for TDM.
Keywords: LC–MS/MS; Dried blood spot; Moxifloxacin; Tuberculosis; Pharmacokinetics; Hematocrit;

Group-selective molecularly imprinted polymer solid-phase extraction for the simultaneous determination of six sulfonamides in aquaculture products by Xizhi Shi; Yuan Meng; Jinghua Liu; Aili Sun; Dexiang Li; Chunxia Yao; Yin Lu; Jiong Chen (1071-1076).
Group-selective molecularly imprinted polymers (MIPs) made from sulfonamides (SAs) using functional monomer methacrylic acid (MAA) were synthesized. The derived molecularly imprinted solid-phase extraction (MISPE) cartridges were developed for the purification and enrichment of aquatic products. The optimum template molecule and the ratio of the functional monomer to the template for obtaining group selectivity to SAs were sulfadimethoxine (SDM) and 4:1, respectively. The MIPs were characterized by Brunauer–Emmett–Teller (BET), scatchard plot, and chromatography analysis, all of which demonstrate better chromatographic behavior and group-selectivity of MIPs for SAs compared with those of corresponding NIPs. The extraction conditions of MISPE for six SAs were optimized; the method precision and accuracy were satisfactory for the fish and shrimp samples at 0.05, 0.1, and 0.2 mg kg−1 spiked levels. Recoveries ranging from 85.5% to 106.1% (RSD, 1.2–7.0%, n  = 3) were achieved. The limits of detection (S/N  = 3) and quantitation (S/N  = 10) in the shrimp and fish samples were achieved from 8.4 to 10.9 μg kg−1 and from 22.4 to 27.7 μg kg−1, respectively. Therefore, the obtained MIPs and MISPE can be employed for the enrichment and clean-up of SAs. This paper presents a new analytical method which enables the simultaneous determination and quantification of SAs in aquaculture products.
Keywords: Molecularly imprinted polymers; Sulfonamides (SAs); Group selectivity; Aquaculture products;

Identification of benzo[c]phenanthridine metabolites in human hepatocytes by liquid chromatography with electrospray ion-trap and quadrupole time-of-flight mass spectrometry by Pavel Kosina; Jan Vacek; Barbora Papoušková; Marie Stiborová; Jakub Stýskala; Petr Cankař; Eva Vrublová; Jitka Vostálová; Vilím Šimánek; Jitka Ulrichová (1077-1085).
The metabolism of the benzo[c]phenanthridine alkaloids was studied using human hepatocytes which are an excellent model system for biotransformation studies. For analysis of the alkaloids and their metabolites, an electrospray quadrupole ion-trap mass spectrometry (ESI ion-trap MS) connected to a reversed phase chromatographic system based on cyanopropyl modified silica was used. The optimized experimental protocol allowed simultaneous analysis of the alkaloids and their metabolites and enabled study of their uptake into and interconversion in human hepatocytes. The results show that formation of the dihydro metabolite which may be followed by specific O-demethylenation/O-demethylation processes, is probably the main route of biotransformation (detoxification) of the benzo[c]phenanthridines in human hepatocytes. The structure of the main O-demethyl metabolite (2-methoxy-12-methyl-12,13-dihydro-[1,3]dioxolo[4′,5′:4,5]benzo[1,2-c]phenanthridin-1-ol; 336.1 m/z,) was proposed by the multi-stage MS and quadrupole time-of-flight MS methods using chemically synthesized standard.
Keywords: Sanguinarine; Chelerythrine; Mass spectrometry; Biotransformation; Reduction and oxidation; Human hepatocytes;

Ultra performance liquid chromatography (UPLC) provides improved resolution, speed and sensitivity compared to conventional high performance liquid chromatography (HPLC). In this study, a robust UPLC–ESI–MS/MS method was developed for the rapid determination of nine hydroxylated polybrominated diphenyl ethers (OH-PBDEs) in rat plasma. Under the optimized conditions, the OH-PBDE congeners were eluted within 7.0 min. The limits of quantification defined at the signal-to-noise ratio of 10 were 0.17–2.78 ng/mL in rat plasma. The method provided good linearity for the calibration curves with recoveries of 93.3–114.0% and repeatability with relative standard deviation (RSD) of 0.6–5.8% for intra-day and 3.2–10.4% for inter-day measurements. The developed method was applied for supporting the pharmacokinetics investigation of 6-OH-BDE-47 in two groups of Sprague–Dawley rats that received, respectively a single dose of 0.60 mg/kg (high dose) and 0.15 mg/kg (low dose) by intravenous injection. The results showed that plasma levels of 6-OH-BDE-47 declined bi-exponentially with elimination half-life of 71.7 and 85.6 min for lower and higher dose group, respectively. The obtained results of short elimination half-life suggested that 6-OH-BDE-47 might not accumulate significantly in rat.
Keywords: Hydroxylated polybrominated diphenyl ethers; Ultra performance liquid chromatography; Selected reaction monitoring; Pharmacokinetic study;

Development of a reversed phase high performance liquid chromatography method based on the use of cyclodextrins as mobile phase additives to determine pterostilbene in blueberries by Pilar Rodríguez-Bonilla; José Manuel López-Nicolás; Lorena Méndez-Cazorla; Francisco García-Carmona (1091-1097).
In this work, a reversed phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of pterostilbene in food samples. The novel method is based on the addition of cyclodextrins (CDs) to the mobile phase where the complexation of pterostilbene by CDs is carried out. In order to select the most suitable conditions for the RP-HPLC method, the effect of several physico-chemical parameters on the complexation of pterostilbene by CDs was studied. Our results show that the addition of 12 mM HP-β-CD to a 50:50 (v/v) methanol:water mobile phase at 25 °C and pH 7.0 significantly improves the main analytical parameters. In addition, it was seen that pterostilbene forms a 1:1 complex with HP-β-CD, showing an apparent complexation constant of 251 ± 13 M−1. Finally, in order to study the validity of the proposed method, blueberries were analyzed and the concentration of pterostilbene has been determined.
Keywords: Pterostilbene; Cyclodextrins; Reversed phase high performance liquid chromatography; Blueberry;

We report the development of a sensitive liquid chromatography–tandem mass spectrometric assay to quantitate 3-methoxysalicylamine (3-MoSA) in biological samples. Derivatization with 1,1′-thiocarbonyldiimidazole followed by C18 reverse-phase chromatography allowed the detection of both analyte and internal standard (hexylsalicylamine) using electrospray ionization and selected reaction monitoring (SRM) in positive ion mode. We monitored the transitions from m/z 196.7 to 65.1 and from m/z 250.1 to 77.1 for 3-MoSA and HxSA, respectively. The method is validated with respect to linearity (r 2  = 0.995), precision (<17% RSD), recovery (100% for 3-MoSA and HxSA), and stability (77% after storage up to 7 month at −80 °C). The LOD and LOQ were 16.12 and 48.87 μg/l, respectively and the LLOQ of 1 pg/ml. In addition, we used this assay to analyze the pharmacokinetics of 3-MoSA in mouse plasma and tissues following both intraperitoneal and oral administration, providing new information regarding the distribution of this compound in vivo.
Keywords: 3-Methoxysalicylamine (3-MoSA); Hexylsalicylamine (HxSA); LC–MS/MS; 1,1′-Thiocarbonyldiimidazole (TCDI); Mouse tissue; Pharmacokinetics;

Strategies for the purification and characterization of protein scaffolds for the production of hybrid nanobiomaterials by Germán Plascencia-Villa; Jimmy A. Mena; Ricardo M. Castro-Acosta; Julio César Fabián; Octavio T. Ramírez; Laura A. Palomares (1105-1111).
Rotavirus VP6 self-assembles into high order macrostructures useful as novel scaffolds for the construction of multifunctional hybrid nanobiomaterials. This application requires large quantities of high quality pure material with strict structural consistency. Strategies for obtaining high quality recombinant VP6 and different characterization techniques are explored and compared in this work. VP6 was expressed in the insect cell–baculovirus system. VP6 assemblies were selectively purified utilizing an ion exchange and size exclusion (SE) chromatography. Purification steps were monitored and characterized by dynamic light scattering (DLS), ELISA, SDS-PAGE, HPLC and Western blot. DLS showed that the initial ultrafiltration step removed small particles, the intermediate anion exchange chromatographic step completely removed the baculovirus, whereas the final size exclusion chromatography permitted the selective recovery of correctly assembled VP6 nanotubes and discrimination of non-assembled VP6, as confirmed by transmission electron microscopy. VP6 assembled into tubular structures with diameter of 75 nm and several nanometers in length. The purification yield was 20% of multimeric assemblies with a purity >98%. The resulting material was suitable for the production of functionalized hybrid nanobiomaterials through in situ synthesis of metallic nanoparticles.
Keywords: Rotavirus; Nanobiomaterials; Chromatography; Multimeric proteins; Baculovirus;

Automated analysis of mouse serum peptidome using restricted access media and nanoliquid chromatography–tandem mass spectrometry by Geun-Cheol Gil; Jim Brennan; Dan J. Throckmorton; Steven S. Branda; Gabriela S. Chirica (1112-1120).
We demonstrate use of restricted access media with reversed phase functionality (RAM-RP) for analysis of low molecular weight proteins and peptides in mouse serum (75 μl) using a custom designed modular automated processing system (MAPS). RAM-RP fractionation with simultaneous removal of high molecular weight and high abundance proteins is integrated with a follow-on buffer exchange module (BE) to ensure compatibility with subsequent processing steps (trypsin digestion and intact peptide separation prior to mass spectrometric analysis). The high sample capacity afforded by chromatographic methods generates enough sample to achieve comprehensive serum peptidome identification (357 proteins) through tandem mass spectrometric analysis of both intact and digested peptides. Sample losses during transfer between modules are minimized through precise fluidic control; no clogging occurred over several months of serum processing in our low back pressure system. Computer controlled operation of both modules and thorough optimization yield excellent run-to-run reproducibility and protein/peptide overlap in analytical repeats. The robustness of our results demonstrate that the RAM-RP-BE workflow executed on our MAPS platform shows tremendous potential for high throughput peptidome processing, particularly with regard to direct analysis of small-volume serum samples.
Keywords: Proteomics; Peptidomics; Serum; Mouse; Restricted access media; LC–MSMS; On-line processing; Automation;

A sensitive and accurate method for the simultaneous determination of five alkaloids, namely 9α-hydroxymatrine (M1), matrine (M2), sophoridine (M3), oxymatrine (M4), alopecurin A (M5) in different parts (seed, legume, stem, and root) and different harvest times of Sophora alopecuroides L. was developed by high performance liquid chromatography (HPLC) with photodiode array detector (PDA) for the first time. The separation by gradient elution was achieved on Scienhome Kromasil C18 (4.6 × 250 mm, 5 μm) column at 30 °C with acetonitrile (A)/0.1% phosphatic acid + 0.1% triethylamine (B) as the mobile phase. The detection wavelength was 205 nm. The optimized method provided a good linear relation (r  ≥ 0.9993 for all the target compounds), satisfactory precision (RSD values less than 2.3%) and good recovery (96.4–103.6%). The limits of detection ranged between 0.11 × 10−3 and 4.70 × 10−3  μg for the different analytes. The method was successfully applied to analysis and quality control of alkaloid extracts from the traditional Chinese herbal drugs of S. alopecuroides L.
Keywords: Sophora alopecuroides L.; Alkaloids; Harvest time; HPLC;

Chromatography–mass spectrometry studies on the metabolism of synthetic cannabinoids JWH-018 and JWH-073, psychoactive components of smoking mixtures by Andrej Grigoryev; Sergey Savchuk; Aleksandra Melnik; Natal’ja Moskaleva; Jurij Dzhurko; Mihail Ershov; Aleksandr Nosyrev; Aleksandr Vedenin; Boris Izotov; Irina Zabirova; Vladimir Rozhanets (1126-1136).
The Russian Federation prohibited the distribution of herbal mixtures with synthetic aminoalkylindoles JWH-018 and JWH-073, agonist cannabinoid receptors, on January 22, 2010. The lack or low content of their native compounds in urine requires detailed identification of their metabolites, which are excreted with urine and are present in blood. Using gas and liquid chromatography–mass spectrometry, we identified a series of metabolites in urine samples from humans and rats that were products of the following reactions: (a) mono- and dihydroxylation of the parent compounds with hydroxyl groups located at aromatic and aliphatic residues, (b) carboxylation, (c) N-dealkylation and (d) N-dealkylation and hydroxylation. The prevailing urinary metabolites in humans are monohydroxylated forms, while N-dealkylated and N-dealkyl monohydroxylated forms are found in rats. Twenty-six samples of herbal smoking mixtures with JWH-018, purchased in Russia, were analysed.
Keywords: JWH-018; JWH-073; Herbal mixture; Metabolites; GC–MS; LC–MS;

A simple chromatographic assay based on ultra high performance liquid chromatography with ultraviolet detection at 295 nm is proposed to determinate simultaneously human plasma concentrations of imipenem, doripenem, meropenem and ertapenem. After deproteinization by acetonitrile, carbapenems are separated on a PentaFluoroPhenyl column with a binary gradient elution. This method is specific, accurate, precise (the intra-day and inter-day imprecision and inaccuracy are lower than 15%), sensitive (the limit of quantitation is equal to 0.50 mg/L for imipenem, doripenem, ertapenem, meropenem) and not time consuming (run time = 7 min). An application of this method to measure ertapenem plasma concentrations in burn patients is presented.
Keywords: Doripenem; Ertapenem; Meropenem; Imipenem; Ultra high efficiency chromatography;

Nalmefene and naltrexone are used to block the effects of narcotics and alcohol. In the present work, for the first time a microextraction technique was presented to reduce matrix interferences and improve detection limits of the drugs in urine and plasma samples. Electromembrane extraction (EME) followed by high performance liquid chromatography (HPLC) coupled with ultraviolet (UV) detection was optimized and validated for quantification of nalmefene and naltrexone from biological fluids. The membrane consists 85% of 2-nitrophenyl octyl ether (NPOE) and 15% di-(2-ethylhexyl) phosphate (DEHP) immobilized in the pores of a hollow fiber. A 100 V electrical field was applied to make the analytes migrate from sample solution with pH 2.0, through the supported liquid membrane (SLM) into an acidic acceptor solution with pH 1.0 which was located inside the lumen of hollow fiber. Extraction recoveries in the range of 54% and 75% were obtained in different biological matrices which resulted in preconcentration factors in the range of 109–149 and satisfactory repeatability (2.0 < RSD% < 8.3). The method offers good linearity with estimation of coefficient higher than 0.9946. Finally, it was applied to determination and quantification of drugs in human plasma and urine samples and satisfactory results were yielded.
Keywords: Nalmefene; Naltrexone; Electromembrane; Microextraction; Urine; Plasma;

Validation of high-performance liquid chromatography–tandem mass spectrometry assays for the quantification of eribulin (E7389) in various biological matrices by A.C. Dubbelman; H. Rosing; B. Thijssen; L. Lucas; W. Copalu; J. Wanders; J.H.M. Schellens; J.H. Beijnen (1149-1155).
This paper presents specific and sensitive high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC–MS/MS) assays for the quantification of the novel anticancer agent eribulin in human plasma, whole blood, urine and faeces. These assays, developed to support clinical pharmacological studies with the drug, quantify eribulin concentration ranges of 0.2–100 ng/mL for plasma, 0.5–100 ng/mL for whole blood and urine and 0.1–25 μg/g for faeces, using sample volumes of 500 μL or 250 μg (faeces). Samples were prepared with liquid–liquid extraction, separated on a C18 column with gradient elution and analysed with a triple quadrupole MS, in positive ion mode. A structural analogue of eribulin was used as internal standard for the quantification. The assays were linear with correlation coefficients (r 2) of 0.99 and better, whereby the deviation from nominal concentrations ranged from −8.2 to 8.9% with CV values of maximally 14.2%. Stability assessments demonstrated that eribulin is stable at −20 °C in plasma, whole blood, urine and faeces for at least 38, 4, 10.5 and 5 months, respectively. In conclusion, the validation results show that the assays are specific and accurate and can therefore adequately be applied to support clinical studies of eribulin.
Keywords: Eribulin; E7389; LC–MS/MS; Human mass balance study;