Solid-phase Extraction Liquid Chromatography Research Articles

Synergistic enhancement of glucagon-like peptide-1 release by γ-aminobutyric acid and L-phenylalanine in enteroendocrine cells-searching active ingredients in a water extract of corn zein protein.

This study investigated the glucagon-like peptide-1 (GLP-1)-releasing activity of an aqueous extract (ZeinS) from corn zein protein and aimed to identify the active compounds responsible for this activity. Glucagon-like peptide-1-releasing activity was evaluated using a murine enteroendocrine cell line (GLUTag). Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed on purified fractions of ZeinS to identify active molecules. ZeinS stimulated more GLP-1 secretion from GLUTag cells compared to zein hydrolysate. Fractions displaying biological activity were determined by solid-phase extraction and high-performance liquid chromatography (HPLC) fractionation. Subsequent LC-MS/MS analysis identified several amino acids in the active fractions of ZeinS. In particular, γ-aminobutyric acid (GABA) exhibited significant GLP-1-releasing activity both alone and synergistically with L-phenylalanine (Phe). Moreover, ZeinS-induced GLP-1 secretion was attenuated by antagonists for the GABA receptor and calcium sensing receptor. These results demonstrate that GABA and Phe identified in ZeinS synergistically stimulate GLP-1 secretion in enteroendocrine cells.

Determination of Benzimidazoles in Chicken and Egg Samples by Urea-Based Covalent Organic Polymer (UCOP) Pipette Tip–Solid-Phase Extraction (PT–SPE) and High-Performance Liquid Chromatography–Tandem Mass Spectrometry (HPLC–MS)

A urea-based covalent organic polymer (UCOP), was synthesized using 1,4-phenylene diisocyanate (PPDI) and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) trianiline (TTTA) and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and nitrogen adsorption-desorption isotherm analysis. The prepared material was employed as an adsorbent for pipette tip–solid-phase extraction (PT–SPE) for benzimidazoles before high-performance liquid chromatography–tandem mass spectrometry analysis (HPLC–MS). The parameters affecting the isolation efficiency, including salt concentration, sample pH, mass of adsorbent, and types and volumes of eluent, were optimized. Using these conditions, PT–SPE provided good linearity from 0.1 to 10 μg kg−1 with low limits of detections (LODs) of 0.02 μg kg−1 together with good precision (relative standard deviations from 4.2 to 8.3%) and accuracy (recoveries from 76.2 to 84.8%). The results demonstrate that the urea-based covalent organic polymer has the potential for the enrichment of trace benzimidazoles.

Simultaneous determination of paracetamol and diclofenac in wastewater by high-performance liquid chromatography method

In this study, a simple, selective, and accurate analysis method was developed for the simultaneous determination of anti-inflammatory drugs (paracetamol and diclofenac) existing inlet and outlet of the wastewater treatment system. This method used solid-phase extraction (SPE) and reversed-phase high-performance liquid chromatography with a photodiode array detector (HPLC-PDA). Separation was performed using an HSR C18 column (250 mm × 4.6 mm; 5 µm) with a mobile phase consisting of acetonitrile: sodium dihydrogen orthophosphate in the ratio 60:40 v/v. The flow rate was 1 ml/min, and PDA was detected at 243 nm with paracetamol and 276 nm with diclofenac. The duration of paracetamol and diclofenac was 2.39 and 4.39 min, respectively. The developed method was validated in terms of accuracy, precision, and linearity for two drugs found in the range of 0.01 - 1 µg/ml, and 0.02 - 1 µg/ml for paracetamol, and diclofenac, respectively. The limits of detection for paracetamol and diclofenac were 0.003 µg/ml and 0.006 µg/ml, respectively, whereas the limits of quantification were 0.01 µg /ml and 0.02 µg/ml, respectively. The recoveries for paracetamol and diclofenac were greater than 95 %. The described method also has been applied to determine paracetamol and diclofenac simultaneously in the wastewater of the treatment system.

Porous polymer monoliths with complementary retention mechanisms for online solid-phase extraction liquid chromatography to determine lysozyme in egg white

Porous polymer monoliths with complementary retention mechanisms for online solid-phase extraction liquid chromatography to determine lysozyme in egg white

Development and Validation of a SPE-HPLC Method for Quantification of Rhein, Emodin, Chrysophanol and Physcion in Rhamnus petiolaris Boiss. & Balansa.

Anthraquinones exhibit a significant group of natural and synthetic quinone derivatives because of their biological activities and industrial applications. Rhamnaceae is one of the families known to contain different kinds of anthraquinones. In this study, it was aimed to quantify rhein, emodin, chrysophanol and physcion in fruits of Rhamnus petiolaris Boiss. & Balansa belonging to Rhamnaceae by solid phase extraction and high performance liquid chromatography with ultraviolet detection. The anthraquinones were separated using a C18 analytical column. Gradient elution was performed using a mobile phase consisted of 0.1% o-phosphoric acid solution and methanol. Analytes were detected at 254nm. Calibration curves were prepared in the range of 0.25-5.00μg/mL for rhein, chrysophanol, physcion, 1.00-50.00μg/mL for emodin. Limits of detection and quantification were between 0.07-0.11 and 0.20-0.34μg/mL, respectively. Relative standard deviations were ≤ 5.78% in repeatability and intermediate precision studies. Accuracy was determined as relative mean error (8.17-12.06%). Extraction was achieved by maceration with acetone and ethanol, followed by hydrophilic-lipophilic balance solid phase extraction. Recoveries were between 96.2 and 109.6%. The developed and validated method was successfully performed to quantify rhein, emodin, chrysophanol and physcion in R. petiolaris fruit extracts. Only physcion was not detected above limit of detection.

Hybrid Targeted/Untargeted Screening Method for the Determination of Wildfire and Water-Soluble Organic Tracers in Ice Cores and Snow.

Wildfires can influence the earth's radiative forcing through the emission of biomass-burning aerosols. To better constrain the impacts of wildfires on climate and understand their evolution under future climate scenarios, reconstructing their chemical nature, assessing their past variability, and evaluating their influence on the atmospheric composition are essential. Ice cores are unique to perform such reconstructions representing archives not only of past biomass-burning events but also of concurrent climate and environmental changes. Here, we present a novel methodology for the quantification of five biomass-burning proxies (syringic acid, vanillic acid, vanillin, syringaldehyde, and p-hydroxybenzoic acid) and one biogenic emission proxy (pinic acid) using solid phase extraction (SPE) and ultrahigh-performance liquid chromatography coupled with high-resolution mass spectrometry. This method was also optimized for untargeted screening analysis to gain a broader knowledge about the chemical composition of organic aerosols in ice and snow samples. The method provides low detection limits (0.003-0.012 ng g-1), high recoveries (74 ± 10%), and excellent reproducibility, allowing the quantification of the six proxies and the identification of 313 different molecules, mainly constituted by carbon, hydrogen, and oxygen. The effectiveness of two different sample storage strategies, i.e., re-freezing of previously molten ice samples and freezing of previously loaded SPE cartridges, was also assessed, showing that the latter approach provides more reproducible results.

Application of solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) and comparison of both detection techniques (DAD and FLD) to analyse nesfatin-1 in fetal bovine serum samples

AbstractIn this study, we propose a simple, cost-effective, and sensitive high-performance liquid chromatography with both detection techniques such as diode-array detection and fluorescence detection (HPLC-DAD-FLD) for the determination of nesfatin-1 in fetal bovine serum samples. The limit of detection (LOD) and limit of quantification (LOQ) for nesfatin-1 were set at satisfactory values in the range 0.22–0.35 mg mL−1 and in the range 0.67–1.05 mg mL−1, respectively (at two different wavelengths (DAD) and at four different wavelengths (FLD)). Analyte concentrations were determined as the average value from fetal bovine serum matrix samples. The preliminary results show that the SPE procedure on Isolute Si-TsOH (SCX-3) could be used for further nesfatin-1 analyses in human serum samples. Both the SPE technique, chromatographic analysis with gradient elution mode and detection technique are fast and convenient.

Determination of anti-SARS-CoV-2 virustatic pharmaceuticals in the aquatic environment using high-performance liquid chromatography high-resolution mass spectrometry.

The Covid-19 pandemic has affected the global population since 2019. The rapid development and approval of vaccines has brought relief. Yet, effective cures are still being researched. Even if the pandemic situation may end, SARS-CoV-2 will remain and, thus, continued application of the drugs will lead to emissions of the active ingredients into the aquatic environment, as with other anthropogenic micropollutants. However, a general method for trace analysis of antiviral drugs is still missing. To this purpose, favipiravir, remdesivir, its active metabolite GS-441524, molnupiravir and its active metabolite EIDD-1931 were selected as representative analytes. A method was developed based on solid phase extraction and high-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight high-resolution mass spectrometry. Optimization comprised the choice of chromatographic columns, elution gradient, mass spectrometry and tandem mass spectrometry parameters. Solid phase extraction proved suitable for increase in limits of detection and quantitation. amelioration of the limits of detection and quantitation. Matrix effects were investigated applying the optimized method to a wastewater sample with added virustatics. All five compounds could be separated with reversed phase chromatography, whereas EIDD-1931 profited from hydrophilic interaction liquid chromatography. The optimized method yielded limits of detection and quantification of 2.1·10-1, 6.9·10-1 µg·L-1 for favipiravir, 1.8·10-3, 5.5·10-3 µg·L-1 for remdesivir, 1.9·10-3, 7.6·10-3 µg·L-1 for GS-441524, 2.9·10-3, 8.7·10-3 µg·L-1 for molnupiravir, and 1.3·10-1, 3.8·10-1 µg·L-1 for EIDD 1931. The method was first applied to compound stability testing at pH2.8 and 9.7. At pH2.8, remdesivir, GS-441524 and molnupiravir proved stable, whereas about 14% of EIDD-1931 and favipiravir were degraded. All five antiviral compounds were almost completely decomposed at pH9.7. The application of the method was further demonstrated for potential transformation product detection on favipiravir ozonation monitoring.

Response Surface Method for Simultaneous Separation of Non-Steroidal Anti-Inflammatory Drugs and Tetracyclines in Water Samples using Online Solid Phase Extraction-Liquid Chromatography

Response Surface Method for Simultaneous Separation of Non-Steroidal Anti-Inflammatory Drugs and Tetracyclines in Water Samples using Online Solid Phase Extraction-Liquid Chromatography

Development, validation, and use of a monitoring method for fipronil and its metabolites in chicken eggs by QuEChERS with online-SPE-LC-Q/Orbitrap analysis.

The residues of fipronil and its metabolites in chicken eggs pose a threat to human health, so regular monitoring is necessary. However, the pretreatments of the existing detection methods are complex and time-consuming. A simple and streamlined pretreatment method is needed to improve the detection efficiency. A rapid, efficient, and facile approach employing QuEChERS with online solid-phase extraction liquid chromatography tandem Q-Exactive Orbitrap high resolution mass spectrometry (online-SPE-LC-HRMS) was established and evaluated for the determination of fipronil, fipronil-desulfinyl, fipronil-sulfone and fipronil-sulfide in chicken eggs. An improved sample preparation technique combining QuEChERS and online-SPE was developed. Negative targeted ion fragmentation scanning (t-MS2 ) and targeted-selected ion monitoring (t-SIM) of the HRMS were adopted to identify and quantify the target analytes. The proposed pretreatment method took a few steps in < 13 min to achieve excellent recoveries and negligible interference. High selectivity was acquired with the adoption of Q/Orbitrap HRMS. The LOQ of the analytes was 2.5 μg kg-1 , meeting the detection requirements of the MRL enacted by the Codex Alimentarius Commission (CAC), Japan and USA for the sum of fipronil and its metabolites. Extraction recoveries at three spiked concentration levels were within 84.56-93.84% with RSD ≤ 5.87%. The established method is efficient and easy to operate and displays satisfactory LOQs, recoveries, accuracy and precision. This approach serves as a reference method for monitoring eggs while providing potential solutions for fipronil determination in more complicated matrices.

Water-related atmospheric agents and solubility: two parameters of validation in toxicological screening on clothing worn by skeletal remains

In forensic toxicology, when conventional matrices are no longer available, alternative matrices can be used to assess toxicological investigations. Clothes worn by skeletal remains may be a good unconventional matrix for toxicological analyses considering that they have absorbed decomposition fluids and blood from a body. We hypothesized a scenario in which a skeleton, wearing clothes, was discovered in an open environment. From this starting point, an experimental study was developed on different textiles (cotton, wool, and polyester) to evaluate whether water-related atmospheric agents and molecule solubility can largely influence the detection of molecules of toxicological interest on this specific matrix, together with the characteristics of different garments chosen. The experimental study was performed on blood spots, previously spiked with 6-monoacetylmorphine and morphine, accurately placed on different textiles and washed with different quantities of deionized water adjusted at pH 5.6 with formic acid to simulate different rainfall conditions. Toxicological analyses were performed via Solid-Phase Extraction and High-Performance Liquid Chromatography—Tandem Mass Spectrometry analyses (Thermo Scientific™ TSQ Fortis™ II Triple-Quadrupole Mass Spectrometer). From the experimental study morphine could not be detected on 100% cotton and 100% wool fabric after the passing of 500 mL of deionized water and in 100% synthetic polyester textile after washing with 250 mL of deionized water. In conclusion, when toxicological analyses are carried out on unconventional matrices as textiles worn by corpses exposed to different environmental conditions, it is of great importance, in using such substrates as evidence for the presence of molecules of toxicological interest, to evaluate chemical-physical characteristics of each analyte under investigation in order to correctly interpret the toxicological data obtained.

A Simultaneous Determination of Benzophenone and Camphor UV-Filters, Together with Metabolites of Polycyclic Aromatic Hydrocarbons, in Human Urine

By monitoring biomarkers in urine, personal exposure to selected chemical substances can be assessed. In this paper, we describe the monitoring of 7 benzophenone and 2 camphor UV-filters and 11 metabolites of polycyclic aromatic hydrocarbons (OH-PAHs) in 454 urine samples collected from mothers and new-borns from an industrial (Karvina) and reference area (Ceske Budejovice) over winter and summer seasons. The analytical method consisted of enzymatic hydrolysis, liquid–liquid extraction (ethyl acetate), purification by dispersive solid-phase extraction (Z-Sep sorbent) and ultra-high performance liquid chromatography coupled with tandem mass spectrometry. Benzophenone-1 (BP-1), naphthalen-2-ol (2-OH-NAP), fluoren-2-ol (2-OH-FLUO) and phenanthren-2-ol (2-OH-PHEN) were determined in all urine samples analysed. Benzophenone-3 (BP-3) and 2-OH-NAP were found at the highest concentrations (medians of 5.95- and 5.77-µg/g creatinine). Analytes 3-(4-methylbenzylidene)camphor (3-MBC), 3-benzylidenecamphor (3-BC), chrysen-6-ol (6-OH-CHRY) and benzo(a)pyrene-3-ol (3-OH-BaP) were not detected in any urine sample. Median concentrations of UV-filters and OH-PAHs were compared across regions in the Czech Republic and between mothers and their new-borns from different countries. The median concentrations of UV-filters measured in urine samples from new-borns in our study were similar to samples collected from Brazilian children and the concentrations of these compounds in mothers’ samples were comparable with the concentrations in Danish mothers. In the case of OH-PAHs, the median concentrations of these substances measured in urine samples from Czech new-borns were comparable to median concentrations of these compounds measured in new-born urine from our previous study, and the concentrations in urine collected from Czech mothers were comparable to those reported in Spanish women.

Fe3O4/ZIFs-based magnetic solid-phase extraction for the effective extraction of two precursors with diverse structures in aflatoxin B1 biosynthetic pathway

The aflatoxin B1 (AFB1) early warning technique based on precursors is an effective strategy for the prevention of AFB1 contamination risk. The determination of precursors is imperative to ensure the efficiency of the early warning technique. Herein, a controllable magnetic adsorbent Fe3O4/ZIFs was first introduced for the effective extraction and determination of averantin (AVN) and sterigmatocystin (ST) precursors in cereal by combining magnetic solid-phase extraction (MSPE) and high-performance liquid chromatography (HPLC). Benefiting from the abundant adsorption sites and multifunctional groups matching the analytes, Fe3O4/ZIFs effectively and simultaneously extracted AVN and ST with great differences in polarity and structure via multiple interactions. AVN was extracted by Fe3O4/ZIFs mainly through π–π and hydrophobic interactions, while ST was extracted predominantly by electrostatic interactions and surface complexation. The limits of detection were 0.08 μg kg−1 (AVN) and 0.36 μg kg−1 (ST). The developed method exhibited satisfactory spiked recoveries (79.1%–105.4%) in the determination of AVN and ST in rice. This work provides a novel analytical strategy for further studying AFB1 early warning technique and the formation and transformation of aflatoxins.

Determination of Environmental Estrogens by Polybenzothiophene-based Solid-phase Extraction (SPE) and High-Performance Liquid Chromatography (HPLC)

Porous polybenzothiophene was synthesized using Friedel-Crafts alkylation and applied as a sorbent for phase extraction. In combination with high performance liquid chromatography, a method for the simultaneous determination of the estrogens 17β-estradiol, ethinylestradiol, and diethylstilbestrol was established for environmental samples. Under the optimized conditions, satisfactory linearity was obtained from 2.0 to 1000.0 μg/L with the coefficients of determination (R2) exceeding 0.9977. The limits of detection were less than 0.3 μg/L for all targets, and the relative standard deviations (n = 5) were below 6.7%. The developed procedure was applied for the determination of estrogens in lake water, grass carp, and chicken manure. The recoveries of the targets were from 75.3% to 106.7%, 78.8% to 109.6%, and 89.1% to 114.5%, respectively. Ethinylestradiol was detected in lake water at 5.3 μg/L. None of the target compounds were present in the grass carp. Ethinylestradiol and diethylstilbestrol were observed in chicken manure at 0.9 μg/g and 0.6 μg/g. The developed method was simple and efficient for the determination of trace estrogens in complex samples.

Simultaneous determination of fourteen pharmaceuticals in sewage sludge using online solid-phase extraction-liquid chromatography-tandem mass spectrometry combined with accelerated solvent extraction.

An online solid-phase extraction (SPE) liquid chromatography tandem mass spectrometry method (HPLC-MS/MS) combined with accelerated solvent extraction (ASE) was developed for simultaneous determination of 14 pharmaceuticals in sludge. In the online SPE procedures, ultrapure water with no additives was used as the loading solvent. In addition, low molecular weight targets such as atenolol were difficult to retain on SPE column after acetone was added to the washing solvent. The response signal of analytes can be greatly improved by adding 0.2% formic acid to the mobile phase. Under the optimized conditions, the recoveries of all the analytes ranged between 75.1 and 112%. Moreover, the limit of detections ranged from 1.8 to 7.9 ug/kg. The precision of analytical data was determined with relative standard deviation (RSD) ≤ 4.87%. This method was successfully applied to determine the concentration of pharmaceuticals in sludge.

Rapid Simultaneous Determination of 11 Synthetic Cannabinoids in Urine by Liquid Chromatography-Triple Quadrupole Mass Spectrometry

Synthetic cannabinoids are a series of synthetic substances that mimic the effects of natural cannabinoids and produce a much stronger toxicity than natural cannabinoids, and they have become the most abused family of new psychoactive substances. A solid-phase extraction–liquid chromatography–triple quadrupole/linear ion trap mass spectrometry method has been developed to determine 11 synthetic cannabinoids in rat urine. Oasis HLB cartridge was selected to simultaneously extract synthetic cannabinoids for pretreatment. The effects of the loading solution and elution reagent volume on the recovery were investigated. The optimized acetonitrile proportion and elution reagent volume were determined by both high recovery and low solvent consumption. The results showed that the linear coefficients of determination of 11 types of synthetic cannabinoids ranged from 0.993 to 0.999, the limit of quantitation ranged from 0.01 to 0.1 ng/mL, and the spiked recoveries ranged from 69.90% to 118.39%. The research presented here provides a validated liquid chromatography tandem mass spectrometry method to accurately identify and quantitate synthetic cannabinoid metabolites in urine samples.

HDPairFinder: A data processing platform for hydrogen/deuterium isotopic labeling-based nontargeted analysis of trace-level amino-containing chemicals in environmental water

The combination of hydrogen/deuterium (H/D) formaldehyde-based isotopic methyl labeling with solid-phase extraction and high-performance liquid chromatography–high resolution mass spectrometry (HPLC-HRMS) is a powerful analytical solution for nontargeted analysis of trace-level amino-containing chemicals in water samples. Given the huge amount of chemical information generated in HPLC-HRMS analysis, identifying all possible H/D-labeled amino chemicals presents a significant challenge in data processing. To address this, we designed a streamlined data processing pipeline that can automatically extract H/D-labeled amino chemicals from the raw HPLC-HRMS data with high accuracy and efficiency. First, we developed a cross-correlation algorithm to correct the retention time shift resulting from deuterium isotopic effects, which enables reliable pairing of H- and D-labeled peaks. Second, we implemented several bioinformatic solutions to remove false chemical features generated by in-source fragmentation, salt adduction, and natural 13C isotopes. Third, we used a data mining strategy to construct the AMINES library that consists of over 38,000 structure-disjointed primary and secondary amines to facilitate putative compound annotation. Finally, we integrated these modules into a freely available R program, HDPairFinder.R. The rationale of each module was justified and its performance tested using experimental H/D-labeled chemical standards and authentic water samples. We further demonstrated the application of HDPairFinder to effectively extract N-containing contaminants, thus enabling the monitoring of changes of primary and secondary N-compounds in authentic water samples. HDPairFinder is a reliable bioinformatic tool for rapid processing of H/D isotopic methyl labeling-based nontargeted analysis of water samples, and will facilitate a better understanding of N-containing chemical compounds in water.

Liquid chromatography-tandem mass spectrometry analysis of delamanid and its metabolite in human cerebrospinal fluid using protein precipitation and on-line solid-phase extraction

The penetration of the antituberculosis drug delamanid into the central nervous system is not established. The distribution of delamanid and its major metabolite, DM-6705, into the cerebrospinal fluid requires investigation. A liquid chromatography-tandem mass spectrometry method for the quantification of delamanid and DM-6705 in human cerebrospinal fluid was developed and validated. The calibration range for both analytes was 0.300 – 30.0 ng/mL. The deuterium-labelled analogue of delamanid (delamanid-d4) and OPC-14714 were used as internal standards for delamanid and DM-6705, respectively. Samples were processed by protein precipitation followed by on-line solid-phase extraction and high-performance liquid chromatography on an Agilent 1260 HPLC system. A Phenomenex Gemini-NX C18 (5.0 µm, 50 mm × 2.0 mm) analytical column was used for on-line solid-phase extraction, and a Waters Xterra MS C18 (5.0 µm, 100 mm × 2.1 mm) analytical column for chromatographic separation using gradient elution, at a flow rate of 300 µL/min. The total run time was 7.5 min. Analytes were detected by multiple reaction monitoring on an AB Sciex 5500 triple quadrupole mass spectrometer at unit mass resolution, with electrospray ionization in the positive mode. Accuracy and precision were assessed over three independent validation batches. Extraction recoveries were more than 98% and were consistent across the analytical range. Both analytes in CSF exhibited non-specific adsorption to polypropylene tubes. The method was used to analyse cerebrospinal fluid samples from patients with pulmonary tuberculosis in an exploratory pharmacokinetic study.

Genome mining and chemical characterization of a new cyclic lipopeptide associated with MDN-0066 from Pseudomonas moraviensis HN2 cultured in a valine-rich medium.

A new cyclic lipopeptide (CLP) MDN-0066-β (1) and MDN-0066 (2) were isolated and characterized from the bacterial cultures of P. moraviensis HN2 in this study. The CLPs were purified by solid-phase extraction (SPE) and reversed-phase high performance liquid chromatography (RP-HPLC). Moreover, chemical structures of two CLPs were characterized by genome mining and analysis, nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HR-MS), Marfey's method and (C-H)α NMR fingerprint matching approach. MDN-0066 (2) has an amino acid sequence of L-Leu1, D-Glu2, D-allo-Thr3, D-Leu4, D-Leu5, D-Ser6, L-Leu7, L-Ile8 linked to a saturated C10 β-hydroxyl fatty acid moiety (R-configuration for 3-OH). The new CLP MDN-0066-β (1) differs MDN-0066 (2) in the 8th position of L-valine in its peptide moiety, this variation in structure could be attributed to the supplement of L-valine in the cultural medium during liquid fermentation. Further antimicrobial tests showed that the two CLPs display moderate antagonistic activity against Staphylococcus aureus and Escherichia coli.

Simultaneous online SPE-HPLC-MS/MS quantification of gefitinib, osimertinib and icotinib in dried plasma spots: Application to therapeutic drug monitoring in patients with non-small cell lung cancer

Gefitinib, osimertinib and icotinib are the most commonly used tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) with EGFR mutation. Therapeutic drug monitoring (TDM) for these TKIs has become a standard and essential procedure. Dried plasma spots (DPS) was choosen for microsampling strategies for TDM, allowing easy and cost-effective logistics in many settings. This study developd and validated an assay for the simultaneous quantitative determination of gefitinib, osimertinib and icotinib in DPS by online solid-phase extraction-liquid chromatography–tandem mass spectrometry (online SPE-LC-MS) system. The TKIs were extracted from DPS with methanol and enriched on a Welch Polar-RP SPE column (30 × 4.6 mm, 5 µm), followed by separation on Waters X Bridge C18 analytical column(4.6 × 100 mm, 3.5 µm). The method achieved LLOQ of 2 ng mL−1 for gefitinib and osimertinib (4 ng mL−1 for icotinib), respectively (r2 > 0.99). Precision (within-run 1.54–7.41 % RSD; between-run 3.03–12.84 % RSD), accuracy (range from 81.47 % to 105.08 %; between-run bias 87.87–104.13 %). Osimertinib and icotinib were stable in DPS stored at − 40 °C for 30 days, 4 °C, 42 °C and 60 °C for 5 days and well-sealed 37 °C,75 % humidity (except gefitinib). Lastly, the assay was applied to TDM of TKIs in 46 patients and the results were compared to SALLE assisted LC-MS analysis, it could be confirmed that the developed method achieves similarly good results as the already established one and no bias could be detected. It implies that this method capable of supporting clinical follow-up TDM of TKIs in DPS from poor medical environment.