Loading...
Publication
Monitoring tranexamic acid in human urine by automatic solid-phase extraction combined with liquid chromatography-mass spectrometry
| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 701.11 KB | Adobe PDF |
Advisor(s)
Abstract(s)
Tranexamic acid (TXA) is an important antifibrinolytic agent in the treatment of different haemorrhagic conditions.1,2 However, the information about pharmacokinetics and pharmacodynamics is scarce. Therefore, the development of analytical methods for the quantification of TXA in different types of biological samples is required, because this information will be relevant in the establishment of adequate doses. TXA has been determined in different biological matrices but the quantification in urine samples assumes particular importance because urinary excretion is the main route of elimination.1,2 Sample preparation is a critical step in analytical procedures for the elimination of interfering compounds and also for analyte pre-concentration.2,3,4 Among the different sample preparation techniques, solid-phase extraction (SPE) is one the most versatile sample-processing methods and the automation of this strategy increases precision by reducing human intervention, sources of error and also analysis time and cost.3,4 Hence, the main goal of the present work was the development of an automated micro-solid-phase extraction (SPE) methodology using bead injection (BI) in a mesofluidic lab-on-valve (LOV) flow system combined to liquid chromatography and mass spectrometry for the determination of TXA in urine samples. For the µSPE-BI-LOV methodology, three sorbents were tested, namely OASIS-HLB, -MCX and -MAX, and different parameters were evaluated, including eluent and carrier composition, composition of matrix removal solution and sample loading volume. All steps of SPE were defined and implemented by computer programming. The processed samples were analysed using a method based on ultra-highperformance liquid chromatography coupled to triple quadrupole-tandem mass spectrometry (UHPLC-MS/MS).5 Chromatographic separation was achieved using a BEH Amide column (50 × 2.1 mm; 1.7 µm particle size), maintained at 40 °C. The mobile phase consisted of a mixture of acetonitrile-aqueous ammonium bicarbonate (pH 7.4; 10 mM), at a flow rate of 0.1 mL min−1. The MS was operated in positive ionization mode (ESI+) and data was acquired in selected reaction monitoring (SRM) mode (m/z 158.25 > 95.15 for quantification, and m/z 158.25 > 123.20 for identification). Firstly, studies were performed using TXA standards, in order to establish the optimal conditions for SPE. The results revealed that OASISHLB sorbent permitted to achieve higher recovery percentages (ca. 80%) and higher repeatability compared to the other tested sorbents, particularly OASIS-MCX. Consequently, OASIS-HLB was selected for the further experiments. The eluent composition and the sample loading volume were also studied, and the best results were obtained using a mixture of acetonitrile-aqueous ammonium bicarbonate (pH 7.4; 10 mM) (75:25, v/v) and 1000 µL of sample, respectively. Furthermore, the use of 0.1% (v/v) of formic acid as washing solution and solvent for sample preparation permitted to increase analyte recovery from 55% to 80%. The use of aqueous ammonium bicarbonate (pH 7.4; 10 mM) or water as carrier was also tested, and the obtained analyte recoveries were similar. The method is currently under development targeting the application to urine samples recovered during scoliosis surgery and the implementation of a strategy for hyphenation of the automated SPE system with mass spectrometry.
Description
Keywords
Tranexamic acid
Citation
Fernandes, S. R., Barreiros, L., Sá, P., Miró, M., & Segundo, M. A. (2019). Monitoring tranexamic acid in human urine by automatic solid-phase extraction combined with liquid chromatography-mass spectrometry. 11th National Chromatography Meeting, 79. https://11enc.eventos.chemistry.pt/images/Book_of_abstracts.pdf
Publisher
Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa
CC License
Without CC licence