Quantitative mass spectrometry methods for pharmaceutical analysis Loos, Glenn; Van Schepdael, Ann; Cabooter, Deirdre
Philosophical transactions - Royal Society. Mathematical, Physical and engineering sciences/Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences,
10/2016, Volume:
374, Issue:
2079
Journal Article
Peer reviewed
Open access
Quantitative pharmaceutical analysis is nowadays frequently executed using mass spectrometry. Electrospray ionization coupled to a (hybrid) triple quadrupole mass spectrometer is generally used in ...combination with solid-phase extraction and liquid chromatography. Furthermore, isotopically labelled standards are often used to correct for ion suppression. The challenges in producing sensitive but reliable quantitative data depend on the instrumentation, sample preparation and hyphenated techniques. In this contribution, different approaches to enhance the ionization efficiencies using modified source geometries and improved ion guidance are provided. Furthermore, possibilities to minimize, assess and correct for matrix interferences caused by co-eluting substances are described. With the focus on pharmaceuticals in the environment and bioanalysis, different separation techniques, trends in liquid chromatography and sample preparation methods to minimize matrix effects and increase sensitivity are discussed. Although highly sensitive methods are generally aimed for to provide automated multi-residue analysis, (less sensitive) miniaturized set-ups have a great potential due to their ability for in-field usage.
This article is part of the themed issue ‘Quantitative mass spectrometry’.
•The degradation of 4 selected pharmaceuticals via BDD electrochemical oxidation was evaluated.•All compounds were readily degraded, although the degradation of iopromide was slower.•A kinetic ...evaluation confirmed that first order kinetics are applicable.•Kinetic constants and activation energies were calculated.•Transformation products were identified and their further degradation was monitored qualitatively.
This study assesses the degradation by electrochemical oxidation via boron doped diamond (BDD) electrodes of the selected pharmaceutical compounds iopromide (IOP), sulfamethoxazole (SMX), 17-alpha-ethinylestradiol (EE2) and diclofenac (DCF) in simulated wastewater and real hospital effluent wastewater. The influence of the flow rate in the electrochemical cell, applied current, initial compound concentration and wastewater matrix (simulated (SWW) versus real effluent (RWW) wastewater) was evaluated. A kinetic evaluation confirmed that the degradation can be described via pseudo first-order reaction kinetics for all experimental conditions tested. It was shown that SMX, EE2 and DCF degraded readily in SWW and RWW. The degradation of IOP was significantly slower, which is in agreement with previously reported slow degradation kinetics using typical advanced oxidation processes. Activation energies for the degradation reactions were calculated. The flow rate in the electrochemical cell had only a moderate effect on the degradation rate of EE2 and DCF. The applied current, however, had a major effect. The BDD electrochemical oxidation was shown to be an effective technique for removing pharmaceutical components from the effluent of a biological hospital wastewater treatment plant. However, the slower degradation of transformation products should be taken into account, when a full mineralization of the pharmaceuticals is pursued.
The kinetic performance of different zwitterionic hydrophilic interaction liquid chromatography polymer columns is evaluated and compared in-depth. For this purpose, two lab-made monolithic columns, ...synthesized with different crosslinkers, and a commercial particle packed column are considered. It is found that performance evaluation techniques, such as comparing plate height curves or fitted A-, B- and C-terms, obtained by fitting experimental plate height data to a plate height model, are complicated by the determination of a reliable characteristic length. This is due to the very different morphology of these column types, and the heterogeneity of the monolithic columns. The occurrence of a convective flow through the packed particle column further complicates the interpretation of the obtained fitting parameters, as part of the C-term is wrongfully attributed to the A-term. Therefore, the use of the kinetic plot method is suggested for the comparative evaluation of these columns, as kinetic plots do not require the determination of a characteristic length, nor rely on any fitting parameters. With the kinetic plot method, it is demonstrated that the lab-made monolithic columns outperform the packed particle column for plate counts between 10,000 and 800,000. This is attributed to the higher column efficiency of these columns, due to their small domain and skeleton sizes, and their high permeability, resulting from their high external porosity and the occasional occurrence of preferential flow paths.
We discuss the most important plot types for the kinetic performance of liquid chromatography columns and elaborate on how these plots should best be constructed and can be made dimensionless. ...Distinction is made between plots that are most suited for practitioners (column users) versus those most suited for theoreticians and column manufacturers.
Zebrafish (Danio rerio) is increasingly used to assess the pharmacological activity and toxicity of compounds. The spatiotemporal distribution of seven fluorescent alkyne compounds was examined ...during 48 h after immersion (10 µM) or microinjection (2 mg/kg) in the pericardial cavity (PC), intraperitoneally (IP) and yolk sac (IY) of 3 dpf zebrafish eleuthero-embryos. By modelling the fluorescence of whole-body contours present in fluorescence images, the main pharmacokinetic (PK) parameter values of the compounds were determined. It was demonstrated that especially in case of short incubations (1-3 h) immersion can result in limited intrabody exposure to compounds. In this case, PC and IP microinjections represent excellent alternatives. Significantly, IY microinjections did not result in a suitable intrabody distribution of the compounds. Performing a QSPkR (quantitative structure-pharmacokinetic relationship) analysis, LogD was identified as the only molecular descriptor that explains the final uptake of the selected compounds. It was also shown that combined administration of compounds (immersion and microinjection) provides a more stable intrabody exposure, at least in case of a prolonged immersion and compounds with LogD value > 1. These results will help reduce the risk of false negative results and can offer an invaluable input for future translational research and safety assessment applications.
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•eAOP efficiency evaluated by UHPLC-QTOF-MS and in vivo estrogenic bioassay.•Over 99.9% EE2 removal obtained at optimal conditions.•Estrogenic activity decreases following the ...degradation of EE2.•Electro-generated radicals readily attack phenolic moiety of EE2.•79 transformation products identified and monitored.
Conventional water treatment methods are not efficient in eliminating endocrine disrupting compounds (EDCs) in wastewater. Electrochemical Advanced Oxidation Processes (eAOPs) offer a promising alternative, as they electro-generate highly reactive species that oxidize EDCs. However, these processes produce a wide spectrum of transformation products (TPs) with unknown chemical and biological properties. Therefore, a comprehensive chemical and biological evaluation of these remediation technologies is necessary before they can be safely applied in real-life situations. In this study, 17α-ethinylestradiol (EE2), a persistent estrogen, was electrochemically degraded using a boron doped diamond anode with sodium sulfate (Na2SO4) and sodium chloride (NaCl) as supporting electrolytes. Ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry was used for the quantification of EE2 and the identification of TPs. Estrogenic activity was assessed using a transgenic medaka fish line. At optimal operating conditions, EE2 removal reached over 99.9% after 120 min and 2 min, using Na2SO4 and NaCl, respectively. The combined EE2 quantification and in vivo estrogenic assessment demonstrated the overall estrogenic activity was consistently reduced with the degradation of EE2, but not completely eradicated. The identification and time monitoring of TPs showed that the radical agents readily oxidized the phenolic A-ring of EE2, leading to the generation of hydroxylated and/or halogenated TPs and ring-opening products. eAOP revealed to be a promising technique for the removal of EE2 from water. However, caution should be exercised with respect to the generation of potentially toxic TPs.
•Performance comparison of HPLC and UHPLC columns in HILIC and RP is given.•HILIC columns have higher permeability caused by high external porosity.•Performance data are expressed as a function of ...the interstitial velocity.•Reduction in analysis time by switching from HPLC to UHPLC in HILIC and RP is similar.
An intrinsic performance comparison is made of the reduction in analysis time that can be obtained when switching from HPLC to UHPLC column formats in HILIC and reversed-phase conditions. A detailed overview of the packing characteristics of both stationary phase types is given first. It is demonstrated that HILIC columns demonstrate higher external porosity values than their reversed-phase counterparts resulting in lower flow resistance values. Column total porosity values determined from the elution time of a small marker molecule are shown to depend strongly on the composition of the mobile phase. To omit errors that might arise from an over- or underestimation of the column void time, all plate height and kinetic plot data are therefore expressed as a function of the interstitial velocity. Although only a limited number of columns are evaluated in this study, it is shown that the column efficiency of the HILIC columns is lower than that of their reversed-phase counterparts, at least for the compounds evaluated here. Despite this lower efficiency, the kinetic performance of both stationary phase types is similar, due to the much lower viscosity of the mobile phases typically used in HILIC conditions. Finally, it is demonstrated that a similar, yet slightly larger reduction in analysis time can be obtained when switching from HPLC column formats to UHPLC formats in HILIC compared to reversed-phase conditions.
•Intra-particle diffusion is compared in RPLC and HILIC columns with identical packings.•Intra-particle diffusion is affected by mesopore diffusion and stationary phase diffusion.•Stationary phase ...diffusion in RPLC is almost twice as large as in HILIC.•Mesopore diffusion in HILIC is larger than in RPLC due to the more-open porous pores.•The extent to which stationary phase and mesopore diffusion affect intra-particle diffusion depends on k”.
A recently developed stripping protocol to completely remove the stationary phase of reversed-phase liquid chromatography (RPLC) columns and turn them into hydrophilic interaction liquid chromatography (HILIC) columns with identical packing characteristics is used to study the underlying mechanisms of intra-particle diffusion in RPLC and HILIC. The protocol is applied to a column with a large geometrical volume (250×4.6mm, 5μm) to avoid extra-column effects and for compounds with a broad range in retention factors (k” from ∼0.6 to 8). Three types of behavior for the intra-particle diffusion (Dpart/Dm) in RPLC versus HILIC can be distinguished: for nearly unretained compounds (k”<0.6), intra-particle diffusion in HILIC is larger than in RPLC; for compounds with intermediate retention behavior (k”∼0.9–1.2), intra-particle diffusion in HILIC and RPLC are similar; and for well retained compounds (k”>1.8), intra-particle diffusion in RPLC is larger than in HILIC. To explain these observations, diffusion in the stationary phase (γsDs) and in the stagnant mobile phase in the mesopore zone (γmpDm) are deduced from experimentally determined values of the intra-particle diffusion, using models derived from the Effective Medium Theory. It is demonstrated that the larger intra-particle diffusion obtained for slightly retained compounds under HILIC conditions is caused by the higher mesopore diffusion in HILIC (γmp=0.474 for HILIC versus 0.435 for RPLC), while the larger intra-particle diffusion obtained for strongly retained compounds under RPLC conditions can be related to the much higher stationary phase diffusion in RPLC (γsDs/Dm=0.200 for RPLC versus 0.113 for HILIC).
•Use of HILIC for the analysis of antibiotics is reviewed.•Specific applications of HILIC for different classes of antibiotics are discussed.•ESI-MS/MS is the most popular detection method in HILIC ...separation of most antibiotics.•It provides comprehensive insight into HILIC application to antibiotics analysis.
This paper presents a general overview of the application of hydrophilic interaction chromatography (HILIC) in the analysis of antibiotics in different sample matrices including pharmaceutical, plasma, serum, fermentation broths, environmental water, animal origin, plant origin, etc. Specific applications of HILIC for analysis of aminoglycosides, β-lactams, tetracyclines and other antibiotics are reviewed. HILIC can be used as a valuable alternative LC mode for separating small polar compounds. Polar samples usually show good solubility in the mobile phase containing some water used in HILIC, which overcomes the drawbacks of the poor solubility often encountered in normal phase LC. HILIC is suitable for analyzing compounds in complex systems that elute near the void in reversed-phase chromatography. Ion-pair reagents are not required in HILIC which makes it convenient to couple with MS hence its increased popularity in recent years. In this review, the retention mechanism in HILIC is briefly discussed and a list of important applications is provided including main experimental conditions and a brief summary of the results. The references provide a comprehensive overview and insight into the application of HILIC in antibiotics analysis.
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