Journal of Chromatography B, 997 (2015) 64–69

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Simultaneous quantification of trantinterol and its metabolites in human urine by ultra performance liquid chromatography–tandem mass spectrometry Feng Qin, Lijuan Wang, Kunjie Li, Zhili Xiong, Famei Li ∗ Department of Analytical Chemistry, School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang 110016, PR China

a r t i c l e

i n f o

Article history: Received 2 February 2015 Received in revised form 1 May 2015 Accepted 9 May 2015 Available online 14 May 2015 Keywords: Trantinterol Metabolites UPLC–MS/MS Human urine Excretion

a b s t r a c t A rapid, selective and sensitive ultra performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed to simultaneously determine trantinterol and its major metabolites in human urine. Waters Oasis HLB C18 solid phase extraction cartridges were used in the urine sample preparation. The separation was carried out on an ACQUITY UPLCTM BEH C18 column with methanol-0.2% formic acid (30:70, v/v) as the mobile phase at a flow rate of 0.25 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via electrospray ionization (ESI) source. The linear calibration curves for trantinterol, arylhydroxylamine trantinterol (N-OH-trantinterol), the tert-butyl hydroxylated trantinterol (tert-OH-trantinterol) and the 1-carbonyl trantinterol (trantinterol-COOH) were obtained in the concentration range of 0.414–207, 0.578–385, 0.168–84.0, and 0.954–477 ng/mL, respectively. The linear correlation coefficients were greater than 0.990. The intra and inter-day precision (relative standard deviation, RSD) values were less than 12% and the accuracy (relative error, RE) was 6.7–11%. The method herein described was superior to previous methods in sample throughput and sensitivity and successfully applied to the human excretion study. © 2015 Elsevier B.V. All rights reserved.

Introduction Trantinterol,2-(4-amino-3-chloro-5-trifluoromethyl-phenyl)2-tert-butylamino-ethanol, is a novel phenylethanolamine ␤2 adrenoceptor agonist currently undergoing phase III clinical trials in China. It has exhibited both a potent trachea relaxing activity and high ␤2 selectivity with low cardiac side effect [1]. The arylhydroxylamine trantinterol (N-OH-trantinterol), the tert-butyl hydroxylated trantinterol (tert-OH-trantinterol) and the 1-carbonyl trantinterol (trantinterol-COOH) are the major metabolites of trantinterol in vivo [2]. Few methods have been reported for the quantification of trantinterol in biological fluids [3–5]. And only one published literature reported a LC–MS/MS method [6] for the simultaneous determination of trantinterol and its major metabolites in rat urine and feces. But this methods needed the long analysis time

Abbreviations: N-OH-trantinterol, arylhydroxylamine trantinterol; tert-OHtrantinterol, the tert-butyl hydroxylated trantinterol; trantinterol-COOH, the 1-carbonyl trantinterol; RSD, relative standard deviation; RE, relative error. ∗ Corresponding author. Tel.: +86 24 2398 6289; fax: +86 24 2398 6289. E-mail address: [email protected] (F. Li). 1570-0232/© 2015 Elsevier B.V. All rights reserved.

(>5.2 min) and complicated and time consuming sample pretreatment procedure, which could not well meet the requirement for high throughput and speed in biosample analysis. Here we present a fast, sensitive and selective UPLC–MS/MS method using solid phase extraction for sample preparation for measuring trantinterol and its three major metabolites in human urine. The total run time of the method per sample was 2.6 min. The present method has been proved to be more efficient in analyzing large number of samples in biological fluids. 2. Experimental 2.1. Chemicals and reagents Trantinterol hydrochloride (of 99% purity) was generously supplied by the Department of Pharmaceutical Chemistry, Shenyang Pharmaceutical University (Shenyang, China). NOH-trantinterol was synthesized in our laboratory. tert-OHtrantinterol, trantinterol-COOH were isolated and purified in our laboratory. The purities of these metabolites were above 99.0%, verified using HPLC. Clenbuterol (internal standard, IS, 99.4% of purity) was purchased from the National Institute for Control of Pharmaceutical and Biological Products (Beijing, PR China). Methanol of

F. Qin et al. / J. Chromatogr. B 997 (2015) 64–69

HPLC grade was obtained from Tedia (Fairfield, OH, USA). Formic acid (HPLC grade) was purchased from Dikma (Richmond Hill, NY, USA). ␤-Glucuronidase were products of Sigma–Aldrich (St. Louis, MO, USA). Water was double-distilled and filtered through a 0.22 ␮m membrane filter before use. All other reagents were of analytical reagent grade. 2.2. Apparatus and operation conditions 2.2.1. Liquid chromatography The analysis was carried out on an ACQUITYTM UPLC system (Waters Corp., Milford, MA, USA) with cooling autosampler and column oven. An ACQUITY UPLCTM BEH C18 column (50 mm × 2.1 mm, 1.7 ␮m; Waters Corp., Milford, MA, USA) was employed for separation with the column temperature maintained at 40 ◦ C. The mobile phase was composed of methanol-0.2% formic acid (30:70, v/v). The flow rate was set at 0.25 mL/min. The autosampler temperature was kept at 4 ◦ C and 10 ␮L of sample solution was injected. 2.2.2. Mass spectrometric conditions A triple quadrupole tandem mass spectrometer (Micromass® Quattro microTM API mass spectrometer, Waters Corp., Milford, MA, USA) equipped with an electrospray ionization (ESI) interface was used for analytical detection. The ESI source was set in positive ionization mode. Quantification was performed using MRM of the transitions of m/z 311 → m/z 238 for trantinterol, m/z 327 → m/z 254 for N-OH-trantinterol, m/z 327 → m/z 238 for tertOH-trantinterol, m/z 325 → m/z 252 for trantinterol-COOH and m/z 277 → m/z 203 for IS, with scan time of 0.10 s per transition. The optimal MS parameters were as follows: capillary voltage 1.0 kV, source temperature 110 ◦ C and desolvation temperature 450 ◦ C. Nitrogen was used as the desolvation and cone gas with a flow rate of 500–30 L/h, respectively. Argon was used as the collision gas at a pressure of approximately 0.258 Pa. The optimized cone voltage and collision energy for trantinterol, N-OH-trantinterol, tert-OH-trantinterol, trantinterol-COOH and IS was 15, 15, 12, 15, 12 V and 15, 14, 12, 18, 12 V. All data collected in centroid mode were acquired and processed using MassLynxTM NT 4.1 software with QuanLynxTM program (Waters Corp., Milford, MA, USA). 2.3. Preparation of standards and quality control samples Stock solution of N-OH- trantinterol was prepared in 0.2% formic acid solution to give concentration of 77.0 ␮g/mL. The solution was then serially diluted with 0.2% formic acid-methanol (80:20) to provide working standard solutions of desired concentrations (series I standard solutions). The mixed stock solution of trantinterol, tertOH-trantinterol and trantinterol-COOH was prepared in methanol to give concentration of 41.4, 16.8 and 95.4 ␮g/mL. The mixed stock solutions were then serially diluted with water-methanol (80:20) to obtain the desired concentrations (series II standard solutions). Internal standard working solution (124 ng/mL) was prepared by diluting the 124 ␮g/mL stock solution of clenbuterol hydrochloride with water. Calibration standards were prepared daily by spiking 25 ␮L of standard solutions (series I and II) and 100 ␮L 6.5% ascorbic acid solution to 500 ␮L of blank urine. The quality control (QC) samples were prepared with blank urine at LLOQ, low, middle and high concentrations and stored aliquot at −80 ◦ C after preparation. One set of standards and quality controls were analyzed on each analysis day with the same procedure for urine samples as described below. 2.4. Urine sample preparation An 80 ␮L IS solution, 25 ␮L 0.2% formic acid-methanol (80:20) solution, 25 ␮L water-methanol (80:20) and 100 ␮L water were


added to 500 ␮L aliquot of urine sample in a 10 mL glass tube successively. Then, the mixture was loaded onto a Waters Oasis 10 mg HLB solid-phase extraction (SPE) cartridge with flow rate of about 0.5–1 mL/min. All processing was performed on a SPE vacuum manifold. The SPE cartridge was preconditioned with 2 mL of methanol and 2 mL of water successively. Care was taken that the cartridges should not run dry. The SPE cartridge was rinsed with 1 mL of water, and the analytes were eluted with 2 mL of methanol. The eluate was evaporated under a nitrogen stream at 40 ◦ C. The residue was reconstituted in 100 ␮L mobile phase, and an aliquot of 10 ␮L was injected into UPLC–MS/MS system for analysis. To determine total trantinterol, N-OH-trantinterol and tert-OHtrantinterol (free plus conjugated trantinterol, N-OH-trantinterol and tert-OH-trantinterol), 100 ␮L ␤-glucuronidase enzyme solution (24000 units/mL in 0.05 mol/L KH2 PO4 buffer, pH 5.0) was added to a 500 ␮L aliquot of human urine. The mixture was incubated in a water bath at 37 ◦ C for 16 h. After enzymatic hydrolysis, the mixture was treated as described above. Those urine samples whose concentrations were higher than the highest calibration point were diluted appropriately with blank human urine in order to make the concentration within the range of the standard curve before sample preparation. 2.5. Method validation The method was validated for selectivity, linearity, precision, accuracy, extraction recovery, matrix effect and stability according to the FDA guideline for validation of bioanalytical methods [7]. 2.5.1. Selectivity The selectivity was evaluated by comparing the chromatograms of six different batches of blank urine obtained from six subjects with those of corresponding standard urine samples spiked with analytes, IS and urine sample obtained after oral dose of 15 mg trantinterol hydrochloride. 2.5.2. Linearity and LLOQ The calibration curves of trantinterol, N-OH-trantinterol, tertOH-trantinterol and trantinterol-COOH were both constructed using standard urine samples at seven concentrations with weighted (1/x2 ) least squares linear regression in the range of 0.414–207 ng/mL, 0.578–385 ng/mL, 0.168–84.0 ng/mL, and 0.954–477 ng/mL. The LLOQ is defined as the lowest concentration on the calibration curve at which an acceptable accuracy (RE) within ±20% and a precision (RSD) below 20% can be obtained. 2.5.3. Precision and accuracy The intra-day precision and accuracy were evaluated by determining a replicate analysis of QC samples on the same day. The run consisted of a calibration curve and five replicates of each LLOQ, low, mid, and high concentration QC samples. For determining the inter-day accuracy and precision, analysis of three batches of QC samples was performed on different days. 2.5.4. Extraction recovery and matrix effect The extraction efficiency of trantinterol and its metabolites was determined by analyzing five replicates of urine samples at low, mid, and high QC concentration levels for each of analytes. The extraction recovery was calculated by comparing the peak areas obtained from extracted samples spiked with known concentrations of the analytes with those of spiked post-extraction at corresponding concentrations. To evaluate the matrix effect, the analytes at low, mid, and high QC concentration levels were added to the extract of 0.5 mL of blank urine, dried and reconstituted with 100 ␮L of 0.2% formic acid–methanol (80:20). The corresponding


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Table 1 Precision, accuracy, recovery and matrix effect for the determination of trantinterol and its three metabolites in human urine (intra-day: n = 5; inter-day: n = 5 series per day, 3 days). Analyte

Concentrations(ng/mL) Added





0.414 1.04 12.4 166 0.578 1.16 23.1 308 0.168 0.42 5.04 67.2 0.954 2.39 28.6 382

Found (mean ± SD) 0.461 ± 0.032 1.10 ± 0.054 13.0 ± 1.0 166 ± 6.2 0.603 ± 0.046 1.25 ± 0.051 24.2 ± 1.2 308 ± 11 0.165 ± 0.010 0.422 ± 0.018 4.94 ± 0.34 66.8 ± 2.8 1.04 ± 0.046 2.23 ± 0.10 29.8 ± 2.3 383 ± 13

R.S.D. (%) Intra-day


5.9 4.4 3.4 2.4 6.5 3.9 2.9 2.6 3.4 2.7 3 3.1 3.5 2.2 2.7 2

8.8 4.7 9.2 6.5 9.3 2.5 7.8 7.2 11 8.7 8.2 8.5 6.6 10 7.4 5.5

R.E. (%)

Recovery (%) (mean ± SD)

Matrix effect (%) (mean ± SD)

11 6 4.7 0.1 4.3 7.5 4.9 −0.1 −1.9 0.5 −2 −0.5 8.6 −6.7 4.3 0.3

– 74.9 ± 3.3 75.7 ± 2.8 75.7 ± 2.8 – 93.0 ± 5.8 91.6 ± 4.9 92.0 ± 3.4 – 85.3 ± 5.0 82.3 ± 3.2 82.9 ± 5.2 – 82.2 ± 4.9 79.0 ± 5.0 81.4 ± 6.2

– 88.4 ± 4.4 87.1 ± 4.5 89.1 ± 3.9 – 94.3 ± 3.1 93.4 ± 2.2 93.0 ± 8.4 – 101.2 ± 6.5 100.2 ± 5.6 100.6 ± 7.9 – 109.4 ± 5.9 105.1 ± 4.0 105.1 ± 3.4

-, not determined.

peak areas (A) were compared with those of the standard solucontaining equivalent amounts of the analytes (B). The ratio tions  A × 100 %was used to evaluate the matrix effect. The extraction B recovery and matrix effect of IS were also evaluated using the same procedure. 2.5.5. Stability The stability of trantinterol and its metabolites in human urine was assessed by analyzing replicates (n = 3) of low and high QC samples during the sample storage and processing procedures. QC samples were stored at −80 ◦ C for 10 days and at ambient temperature for 4 h to determine long-term and short-term stability, respectively. The freeze/thaw stability was evaluated after three complete freeze/thaw cycles on consecutive days. Post-preparation stability was estimated by analyzing QC samples at 0–10 h in the autosampler at 4 ◦ C. 2.6. Application of the assay to the excretion study The clinical excretion study was approved by the local Ethics Committee and carried out in the hospital. Two volunteers who provided written signed informed consent participated in the study according to the principles of the Declaration of Helsinki and 15 mg trantinterol hydrochloride was oral administered to each healthy male volunteer after 12 h fasting. Urine samples were collected into containers surrounded by ice at the time intervals of 0–1, 1–2, 2–4, 4–6, 6–12, 12–24, 24–36, 36–48, and 48–72 h. The volumes of urine were recorded. In order to stabilize N-OH-trantinterol, ascorbic acid was added into the urine sample to make a solution that containing 1.0% ascorbic acid [6]. All samples collected were stored at −80 ◦ C until analysis. The total volume of each sample collected in each time interval was recorded. After centrifugation at 3500 rpm for 10 min at 4 ◦ C, the supernatant of urine samples were stored at −80 ◦ C until analysis. Without administration of trantinterol, collected urines were served as the blank.

was extracted from alkalized samples. Our group once used SPE to extract trantinterol and its metabolites from rat urine [2] and it is well known that SPE offers clean extracts, which is of great benefit to the expensive UPLC column. Therefore, SPE was considered. Three SPE cartridges (Waters oasis HLB C18, Phenomenex Strata C18-E, Agela Cleanert C18) were investigated. In view of recovery and matrix effect Oasis HLB C18 cartridge was chosen. In our previous study [6] we had developed a LC–MS/MS method for the determination of trantinterol and its metabolites in rat urine. In this work, UPLC–MS/MS operation parameters were carefully optimized for the determination of the analytes based on the previous study. All of those mass spectrometer parameters such as cone voltage, capillary voltage, collision energy of collision induced decomposition (CID), collision gas pressure, desolvation temperature, flow rate of desolvation gas and cone gas, ESI source temperature and the ion transitions chosen for MRM of the analytes were same as our previous study. The separation and ionization of trantinterol and its three metabolites were affected by the composition of mobile phase. Therefore, the selection of mobile phase is important for improving peak shape, detection sensitivity and shortening run time. Methanol was chosen as the organic phase because of higher detection response compared to acetonitrile. Methanol proportion in the mobile phase from 20% to 40% was considered in the following experiment. In view of the retentions and peak shapes of the analytes, total run time, matrix effect and detection sensitivity, 30% methanol was chosen. The ionization of analytes was increased by adding formic acid in the mobile phase. All analytes were found to have higher response and better peak shapes whenthe mobile phase containing 0.2% formic acid in aqueous phase. Under the optimal conditions, the total run time for each sample was only 2.6 min, with symmetric peak shape and high sensitivity. This method meets the requirement for high sample throughput in bioanalysis.

3. Results and discussion

3.2. Method validation

3.1. Method development

3.2.1. Selectivity Selectivity was determined by comparing the chromatograms of six different batches of blank human urine with the corresponding spiked urine. As shown in Fig. 1, no interference from endogenous substance or other metabolites was observed at the retention time of the analytes and IS.

Sample preparation is an important part of an analytical method. In our previours study [6] a two-step liquid-liquid extraction was selected. Trantinterol-COOH was extracted from acidified samples and then trantinterol, N-OH-trantinterol and tert-OH-trantinterol

F. Qin et al. / J. Chromatogr. B 997 (2015) 64–69


Fig. 1. Representive MRM chromatograms of trantinterol (peak 1, channel 1), N-OH-trantinterol (peak 2, channel 2), Tert-OH-trantinterol (peak 3, channel 3), trantinterolCOOH (peak 4, channel 4) and IS (peak 5, channel 5) in human urine samples. (A) Blank urine sample; (B) blank urine sample spiked with the analytes at the LLOQ and IS; (C) urine sample from a volunteer 6–12 h after oral administration of trantinterol hydrochloride. The retention times for trantinterol, N-OH-trantinterol, Tert-OH-trantinterol, trantinterol-COOH and IS were 2.29, 1.08, 1.60, 1.72 and 2.19 min, respectively.


F. Qin et al. / J. Chromatogr. B 997 (2015) 64–69

3.2.2. Linearity and LLOQ The peak area ratios of analytes (trantinterol, N-OH-trantinterol, tert-OH-trantinterol and trantinterol-COOH) to IS in human urine varied linearly over the concentration range tested (0.414–207, 0.578–385, 0.168–84.0, and 0.954–477 ng/mL). Typical equations for the calibration curves are: y = 9.31 × 10−2 x - 2.83 × 10−4 , r = 0.995 for trantinterol, y = 3.35 × 10−2 x + 1.05 × 10−4 , r = 0.991 for N-OH-trantinterol, y = 1.39 × 10−2 x - 2.41 × 10−4 , r = 0.997 for tert-OH-trantinterol, and y = 3.40 × 10−2 x + 2.83 × 10−4 , r = 0.997 for trantinterol-COOH, respectively. The LLOQ for the four analytes was 0.414, 0.578, 0.168, 0.954 ng/mL in urine. 3.2.3. Precision and accuracy The data of intra and inter-day precision and accuracy for the analytes from QC samples are summarized in Table 1. The precision and accuracy of the present method conform to the criteria for the analysis of biological samples according to the guidance of FDA where the RSD determined at each concentration level is required not exceeding 15% (20% for LLOQ) and RE within ±15% (±20% for LLOQ) of the actual value [7]. 3.2.4. Extraction recovery and matrix effect The extraction recoveries and matrix effects for analytes in human urine samples are summarized in Table 1. The extract recoveries of analytes in urine samples were in the range of 75–93 %. In terms of matrix effects, all the ratios defined as in Section 2 were between 85% and 115%. No significant matrix effect for the analytes and IS was observed. The mean extraction recovery of IS was 87.1 ± 4.3 %. 3.2.5. Stability study The results from all stability tests are presented in Table 2, which demonstrate a good stability of trantinterol and its metabolites over all steps of the determination. The method is therefore proved to be applicable for routine analysis. 3.3. Excretion study application This validated UPLC–MS/MS method was successfully applied to an excretion study of trantinterol in healthy male volunteers following a single oral administration. Fig. 2 shows the urine cumulative excretion curves of free and total trantinterol, free and total N-OH-trantinterol, free and total tert-OH-trantinterol and trantinterol-COOH. After a single oral administration of trantinterol to humans, about 55.4% of administered trantinterol was recovered in urine excreta in the form of trantinterol, N-OHtrantinterol, tert-OH-trantinterol, their glucuronide conjugates and trantinterol-COOH within 72 h post-dose. The level of trantinterol glucuronide conjugate in excreta was higher than those of other quantified metabolites. Most of these metabolites were excreted within 24 h post dose. Trantinterol was mainly excreted as its glucuronide conjugate metabolites with only a minor amount of the parent recovered (2.36%). The urinary recoveries for parent, free Phase-I metabolites, and glucuronides were calculated to be 2.36, 2.81, and 50.2% respectively, indicating that the glucuronide conjugates were the major urinary metabolites of trantinterol in human. Among the metabolites, the trantinterol glucuronide conjugate was the predominant in the urine, with the recoveries of 38.2%. The excretion profiles suggested that the glucuronide conjugations was one of the major clearance pathways of trantinterol. 4. Conclusion Compared with the analytical methods reported previously, the UPLC–MS/MS method proved to be superior with respect to satisfactory selectivity, short chromatographic analysis time

Fig. 2. Urine cumulative excretion percentage-time profiles of trantinterol-COOH, free and total trantinterol, free and total N-OH-trantinterol and free and total TertOH-trantinterol in 2 healthy volunteers after oral administration of trantinterol hydrochloride.

F. Qin et al. / J. Chromatogr. B 997 (2015) 64–69


Table 2 Stability of analytes in human urine samples at low and high QC levels (n = 3). Stability


Added C (ng/ml)

Short-term stability (room temperature for 4 h)


1.04 166 1.16 308 0.420 67.2 2.39 382 1.04 166 1.16 308 0.420 67.2 2.39 382 1.04 166 1.16 308 0.420 67.2 2.39 382 1.04 166 1.16 308 0.420 67.2 2.39 382

N-OH-trantinterol Tert-OH-trantinterol trantinterol-COOH

Three freeze-thaw cycles

Trantinterol N-OH-trantinterol Tert-OH-trantinterol trantinterol-COOH

Long-term stability (at−80 ◦ C for 10 days)

Trantinterol N-OH-trantinterol Tert-OH-trantinterol Trantinterol-COOH

Post-preparation stability (4 ◦ C for 10 h)

Trantinterol N-OH-trantinterol Tert-OH-trantinterol Trantinterol-COOH

of 2.6 min and the sensitivity with an LLOQ of 0.414, 0.578, 0.168 and 0.954 ng/mL for trantinterol, N-OH-trantinterol, TertOH-trantinterol and trantinterol-COOH, respectively. The method has been successfully applied to the excretion study of 15 mg trantinterol hydrochloride given to healthy volunteers. Acknowledgements This work was supported by the National Natural Science Foundation of China (Grant no. 81102505). The authors are thankful to Dr. Li Pan Department of Pharmaceutical Chemistry, Shenyang Pharmaceutical University, for providing the reference standard of trantinterol hydrochloride. References [1] L. Gan, M. Wang, M. Cheng, L. Pan, Trachea relaxing effects and beta2-selectivity of SPFF a newly developed bronchodilating agent, in guinea pigs and rabbits, Biol. Pharm. Bull. 26 (2003) 323–328.

Found C (ng/ml) (mean ± SD) 1.02 168 1.11 305 0.421 65.9 2.34 375 0.993 166 1.09 302 0.401 65.7 2.28 372 0.984 169 1.14 291 0.392 65.6 2.25 376 1.01 175 1.13 311 0.406 68.7 2.49 375

± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

0.083 9.3 0.14 12 0.022 5.4 0.16 21 0.065 5.1 0.065 9.3 0.016 5.1 0.072 15 0.059 8.0 0.068 17 0.023 4.4 0.23 14 0.069 13 0.062 9.9 0.021 5.0 0.14 16

[2] K. Li, F. Qin, L. Jing, F. Li, X. Guo, In vivo and in vitro metabolism of a novel ␤2 -adrenoceptor agonist, trantinterol: metabolites isolation and identification by LC–MS/MS and NMR, Anal. Bioanal. Chem. 405 (2013) 2619–2634. [3] Y. Sun, M. Liu, J. Zhang, Y. Jiang, W. Yu, J.P. Fawcett, J. Gu, Rapid and sensitive assay for trantinterol a novel beta(2)-adrenoceptor agonist, in human plasma using liquid chromatography-tandem mass spectrometry, J. Pharm. Biomed. Anal. 49 (2009) 1056–1059. [4] J. Yang, Y. Wang, L. Pan, N. Li, X. Lu, J. Guan, M. Cheng, F. Li, Enantioselective determination of trantinterol in rat plasma by ultra performance liquid chromatography–electrospray ionization mass spectrometry after derivatization, Talanta 79 (2009) 1204–1208. [5] L. Jing, K. Li, F. Qin, X. Wang, L. Pan, Y. Wang, M. Cheng, F. Li, Determination of l-trantinterol in rat plasma by using chiral liquid chromatography-tandem mass spectrometry, J. Sep. Sci. 35 (2012) 2678–2684. [6] K. Li, Y. Wang, L. Zhang, F. Qin, X. Guo, F. Li, Simultaneous determination of trantinterol and its metabolites in rat urine and feces by liquid chromatography–tandem mass spectrometry, J. Chromatogr. B. 934 (2013) 89–96. [7] US Food and Drug Administration, Guidance for Industry, Bioanalytical Method Validation, US, FDA, Rockville, MD 2001. Available at downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/ ucm070107.pdf

Simultaneous quantification of trantinterol and its metabolites in human urine by ultra performance liquid chromatography-tandem mass spectrometry.

A rapid, selective and sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to simultaneously ...
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