Positive Electrospray Ionization Mode Research Articles

Glutathione reactivity with aliphatic polyisocyanates.

Isocyanate chemicals known to cause adverse health effects when inhaled are essential to making important products and are used in multiple industries. Glutathione (GSH), a major antioxidant of the lower airways with a well described role in xenobiotic metabolism, is a primary reaction target for di-isocyantes. However, GSHs reactivity with poly-isocyanates which have largely replaced diisocyanates (particularly aliphatic) in most end-user settings remains uncertain. We hypothesized aliphatic polyisocyanates would readily react with glutathione under physiologic conditions and the products could be identified using liquid chromatography (LC) coupled-mass spectrometry (MS) and tandem MS/MS. The data identified (tris)GSH-isocyanate adducts as the major reaction product of GSH with the most commonly used contemporary polymeric (tri-isocyanate) formulations of hexamethylene diisocyanate (HDI), the isocyanurate and biuret, as [M+H]+ ions of 1426.53 and 1400.55 m/z respectively in reverse phase LC-MS using electrospray in positive ion mode. The uretdione form of HDI, a stabilized dimer, formed two reaction products with GSH, a tris(GSH)-isocyanate reaction product recognized as a 1258.44 m/z [M+H]+ ion, and a bis(GSH)-isocyanate product identified as a 951.36 m/z [M+H]+ ion. Predicted structures for the newly described GSH-polyisocyanate reaction products, modeled based on collision induced dissociation (CID) fragmentation patterns in tandem MS/MS, support S-linkage of the GSH to N = C = O groups. In summary, industrially-used aliphatic polyisocyanates readily react with GSH to form primarily S-linked tris(GSH)-conjugates, a process that may play an important role in response to respiratory tract exposure.

A dilute-and-shoot liquid chromatography-tandem mass spectrometry method for urinary 18-hydroxycortisol quantification and its application in establishing reference intervals.

BackgroundEighteen‐hydroxycortisol (18‐OHF) is a potential biomarker for differential diagnosis of the two major primary aldosteronism subtypes, aldosterone‐producing adenoma, and idiopathic hyperaldosteronism.MethodsUrine samples were processed, and the 18‐OHF in urine samples were successfully quantified by in‐house established dilute‐and‐shoot liquid chromatography–tandem mass spectrometry (LC–MS/MS) method. Separation was accomplished on a Sigma Ascentis Express C18 column with a gradient mixture of phase (A) 0.2% formic acid in water and phase (B) 0.2% formic acid in methanol at a flow rate of 0.4 ml/min. Mass spectrometric detection was performed in positive electrospray ionization mode via a mass spectrometer.ResultsThe linearity of urinary 18‐OHF ranged from 4.28 to 8.77 × 103 nmol/L, with a lower limit of quantification at 4.28 nmol/L. The intra‐ and inter‐precision were both below 3%. The range of analytical recovery was 97.8%–109.2%. The validated dilute‐and‐shoot LC–MS/MS method was compared with the SPE LC–MS/MS method modified from the one reported in 2013. The results by Passing–Bablok regression analysis and Bland–Altman plotting demonstrated a good agreement between the two methods. The presented method was then applied to establish sex‐specific reference intervals from 62 males and 62 females, respectively. The calculated 2.5%–97.5% reference intervals for 24‐h urinary 18‐OHF were 113–703 nmol/day for males and 71.2–450 nmol/day for females.ConclusionThe presented dilute‐and‐shoot LC–MS/MS method for 18‐OHF quantification showed a good performance in the clinical application. Furthermore, the sex‐specific reference intervals for 24‐h urinary 18‐OHF were first established and quite important for its application in primary aldosteronism subtyping.

Novel LC–MS Method development and Validation for Characterization of Talazoparib, an Anti-cancer drug and its forced degradation behavior

The present work aimed to develop a novel liquid chromatography and mass spectrometry (LC-MS) method for the determination of Talazoparib (TZPB) in pharmaceutical forms. Analysis of TZPB was performed in mobile phase of Methanol, Acetonitrile and 0.2% Perchloric acid in the ratio of 70:28:02 (v/v) as mobile phase and separation was carried on Prontosil ODS C18 Column (150 X 4.6mm, 5μ) as stationary phase. The degradative property of the TZPB under different stress conditions were evaluated using mass spectral analysis of the eluted compounds. The characterization of column eluents was carried on mass spectrometer operated in a positive ESI (electrospray ionization) mode and analyzed in single quadrupole analyzer. The mass spectra corresponding to molecular weight of TZPB was observed at m/z of 381 and characteristic mass fragmentation was observed in the spectra (m/z of 339 to 204). The linear calibration curve for TZPB was achieved in the range of 0.1–150 ng/mL (r = 0.9994) with a very sensitive detection limit (0.03ng/mL) and quantification limit (0.1ng/mL). The method was validated for parameters such as accuracy, precision, ruggedness, robustness etc and the results of the validation parameters are within acceptable limit at all quality control levels. The forced degradation studied for conditions such as acid, base, oxidation, UV light and thermal degradation conditions. The method can separate and detect the degradation compounds formed during the stress study. The forced degradation compounds formed were characterized using mass spectral study and a total 9 different degradation compounds were identified in the study. Hence the method can apply in identification and quantification of degradation compounds of TZPB in quality control and formulations.

Validated LC/MS/MS Method for the Determination of Rivastigmine in Human Plasma: Application to a Pharmacokinetic Study in Egyptian Volunteers to Determine the Effect of Gender and Body Mass Index.

The effect of gender and body mass index (BMI) on the pharmacokinetics of rivastigmine was studied in Egyptian human subjects using new bio-analytical validated LC/MS/MS method. In this study, Rivastigmine was estimated in human plasma using Escitalopram as an internal standard (IS). Rivastigmine and Escitalopram were extracted from human plasma samples by liquid-liquid extraction using diethyl ether (DEE)-dichloromethane (DCM) (70:30, v/v). Chromatographic separation was performed on a reversed phase C18 INERTSIL ODS column using 0.05% aqueous formic acid, acetonitrile in the ratio (50:50, v/v) as a mobile phase. Multiple reaction monitoring (MRM) was applied and operated by positive mode electrospray ionization. A significant difference between male and female Cmax (maximum plasma concentration) (P= 0.0205; CL = 95.4) was found using Mann-Whitney U test. Also, a moderate negative correlation was found between BMI and Tmax (time to peak plasma concentration) using spearman rho test. The calculated results confirm the difference of Rivastigmine pharmacokinetics between male and female subjects. Furthermore, it indicates that Rivastigmine dose adjustment may be necessary. The method was applied for the estimation of pharmacokinetic parameters in volunteers (n= 26, 17 male and 9 female) and the effects of gender and BMI were investigated.

Rapid Determination of 9 Tyrosine Kinase Inhibitors for the Treatment of Hepatocellular Carcinoma in Human Plasma by QuEChERS-UPLC-MS/MS.

A reliable and rapid method employing QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) pretreatment coupled with ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) was successfully developed and validated for the analysis of nine tyrosine kinase inhibitors (TKIs) in human plasma. Biological samples were extracted with acetonitrile and salted out with 350 mg of anhydrous magnesium sulfate (MgSO4), followed by purification with 40 mg of ethyl enediamine-N-propylsilane (PSA) adsorbents. All analytes and internal standards (IS) were separated on the Hypersil GOLD VANQUISH C18 (2.1 mm × 100 mm, 1.9 μM) column using the mobile phases composed of acetonitrile (phase A) and 0.1% formic acid in water (phase B) for 8.0 min. Detection was performed by selection reaction monitoring (SRM) in the positive ion electrospray mode. Lenvatinib, sorafenib, cabozantinib, apatinib, gefitinib, regorafenib, and anlotinib rendered good linearity over the range of 0.1–10 ng/ml, and 1–100 ng/ml for tivantinib and galunisertib. All linear correlation coefficients for all standard curves were ≥ 0.9966. The limits of detection (LOD) and the limits of quantitation (LOQ) ranged from 0.003 to 0.11 ng/ml and 0.01–0.37 ng/ml, respectively. The method was deemed satisfactory with an accuracy of -7.34–6.64%, selectivity, matrix effect (ME) of 90.48–107.77%, recovery, and stability. The proposed method is simple, efficient, reliable, and applicable for the detection of TKIs in human plasma samples as well as for providing a reference for the clinical adjustment of drug administration regimen by monitoring the drug concentrations in the plasma of patients.

Evaluation of 4 quantification methods for monitoring 16 antibiotics and 1 beta-lactamase inhibitor in human serum by high-performance liquid chromatography with tandem mass spectrometry detection

Antibiotic (ATB) prescription in an intensive care unit (ICU) requires continuous monitoring of serum dosages due to the patient’s pathophysiological condition. Dosing adjustment is necessary to achieve effective targeted concentrations. Since ICUs routinely use a large number of ATBs, global monitoring needs to be developed. In the present study, we developed a global analytical method for extracting, separating and quantifying the most widely used ATBs in ICUs: amoxicillin, piperacillin, cefazolin, cefepime, cefotaxime, ceftazidime, ceftolozane, ceftriaxone, ertapenem, meropenem, ciprofloxacin, moxifloxacin, levofloxacin, daptomycin, dalbavancin, linezolid and a beta-lactamase inhibitor: tazobactam. To guarantee the robustness of the quantification, we differentiated the 16 ATBs and the beta lactamase inhibitor into 4 pools (ATB1 to ATB4), taking into account prescription frequency in the ICU, the physicochemical properties and the calibration ranges of the ATBs selected. The whole ATB was then separated with two LC columns in reversed phase: Kinetex Polar-C18 100 Å and Polar-RP-80 synergy, in less than 6.5 min. Detection was carried out by electrospray in positive ion mode, by tandem mass spectrometry (LC-MS/MS. The four quantification methods were validated according to the European guidelines on bioanalytical method validation (EMEA guide), after determining the extraction yields, matrix effects, recovery, precision, accuracy, within-run precision and between-run precision. For all analyses, bias is < 15% and is comparable to the literature and LOQs vary from 0.05 mg.L−1 for ciprofloxacin to 1.00 mg.L−1 for ceftriaxone and dalbavancin. The stability time of cefepime and piperacillin is 3 hrs and for the other ATBs 6 hrs in serum at room temperature. For long-term stability, freezing at − 80 °C guarantees 3 months of stability for ceftriaxone and dalbavancin and more than 6 months for the other ATBs.

Quantitative Determination of 5-Aminoisoquinoline, a PARP-1 Inhibitor by UPLC-MS/MS: In Silico ADME Profile and In Vitro Metabolic Stability Study

5-Aminoisoquinoline (5-AIQ) is a water-soluble, potent and selective Poly (ADP-ribose) polymerase 1 (PARP-1) inhibitor, widely used as a biochemical and pharmacological tool to study the inhibitory effect of PARPs enzyme. In this study, a simple, selective and reliable ultra-performance liquid chromatography-tandem mass spectrometry assay has been developed for the quantitative analysis of 5-AIQ in plasma using pantoprazole as an internal standard (IS). Both 5-AIQ and IS were separated on an Acquity CSH18 (2.1 × 100 mm; 1.7 µm) column after chromatographic elution of mobile phase comprising of 10 mM ammonium acetate and acetonitrile (35:65; v/v) at a flow rate of 0.3 mL/min. Electrospray ionization in positive mode was used for sample ionization and precursor to product ion transitions of 145.0 &gt; 91.0; 145.0 &gt; 117.4 for 5-AIQ and 384.0 &gt; 138.1 for IS were used for detection and quantification in multiple reaction monitoring mode. The assay was linear in the concentration range of 1.0 to 666 ng/mL with correlation coefficient of ≥0.995. The precision and bias were within the acceptable limits of ≤12.68% and −8.6 to 5.9%, respectively, with mean recovery of 79.1% from plasma and negligible matrix effects (92.4%). In silico ADME prediction, 5-AIQ showed to be very soluble in water and high gastrointestinal absorption along with blood–brain barrier (BBB) permeability. The validated assay was successfully applied in a metabolic stability study, and 5-AIQ was moderately metabolized by human liver microsomes with an in vitro half-life of 14.5 min and intrinsic clearance of 47.6 µL/min/mg. The validated method can be utilized for future pharmacokinetic and bio-distribution studies.

Quantification of N, N’ N’’-triethylenethiophosphoramide, N, N’ N’’-triethylenephosphoramide, cyclophosphamide, and 4-hydroxy-cyclophosphamide in microvolume human plasma to support neonatal and pediatric drug studies

N, N’ N’’-triethylenethiophosphoramide (thiotepa) and cyclophosphamide (CP) are alkylating agents used for a variety of malignant and non-malignant disorders. Both drugs are metabolized by cytochrome P450 enzymes to form active metabolites. To support pharmacokinetic studies of thiotepa and CP in children, we sought to develop assays to determine parent drug and metabolite concentration in small volume plasma samples. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for assay development. CP metabolite 4-hydroxycyclophosphamide (4OHCP) was converted to the more stable semicarbazone derivative (4OHCP-SCZ) for quantitation. Samples (10 µL) were extracted by solid-phase extraction and injected onto the LC-MS/MS system equipped with a pentafluorophenyl reverse phase column (2.1 × 50 mm, 2.7 µm). Electrospray ionization in positive mode was used for detection. Multiple reaction monitoring of the precursor-to-product ion transitions m/z 190→147 for thiotepa, 174→131 for tepa, 261→233 for CP, and 334→221 for 4OHCP-SCZ was selected for quantification. The ion transitions m/z 202→155 for thiotepa-d12, 186→139 for tepa-d12, 267→237 for CP-d4, and 340→114 for 4OHCP-d4-SCZ were selected for the internal standard (IS) corresponding to each analyte. The less abundant IS ions from 37Cl were used for CP-d4 and 4OHCP-d4-SCZ to overcome the cross-talk interference from the analytes. Under optimized conditions, retention times were 0.67 min for tepa and its IS, 2.50 min for thiotepa and its IS, 2.52 min for 4OHCP-SCZ and its IS, and 2.86 min for CP and its IS. Total run time was 5 min per sample. The calibration ranges were 2.5-2,000ng/mL for thiotepa and tepa, 20-10,000ng/mL for CP and 20-5,000 ng/mL for 4OHCP; Dilution integrity for samples above the calibration range was validated with 10-fold dilution for thiotepa/tepa and 20-fold dilution for CP/4OHCP . Recoveries ranged from 86.3-93.4% for thiotepa, 86.3-89.0% for tepa, 90.2-107% for CP, and 99.3-115% for 4OHCP-SCZ. The IS normalized matrix effect was within (100±7) % for all 4 analytes. Plasma samples at room temperature were stable for at least 60 hours for thiotepa, 6 days for tepa, and 24 hours for CP and 4OHCP-SCZ. Plasma samples for thiotepa/tepa were stable after 4 freeze-thaw cycles, and for CP/4OHCP-SCZ were stable after 3 freeze-thaw cycles. The assays were validated and applied to clinical studies requiring small sample volumes.

Development of a Sensitive and High-Throughput Assay for Simultaneous Quantification of 5 Tyrosine Kinase Inhibitors and 2 Active Metabolites in Human Plasma Using Ultra-high Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry.

Breakpoint cluster region-Abelson (BCR-ABL) tyrosine kinase inhibitors (TKIs) demonstrate improved therapeutic efficacy in chronic myeloid leukemia (CML). However, drug-drug interactions, nonadherence, and host-related factors may influence plasma concentrations. Therefore, therapeutic drug monitoring may be necessary for patients presenting inadequate treatment responses or adverse events. Herein, the authors aimed to develop a more sensitive and high-throughput method than those previously reported to simultaneously quantify 5 TKIs (imatinib, nilotinib, dasatinib, bosutinib, and ponatinib) and 2 active metabolites (N-desmethyl imatinib and N-desmethyl ponatinib) using ultra-performance liquid chromatography coupled with tandem mass spectrometry. Plasma samples were prepared according to a solid-phase extraction protocol using an Oasis MCX µElution plate. The assay fulfilled the requirements of the US Food and Drug Administration for assay validation, with a lower limit of quantification of 0.2 ng/mL for dasatinib, 0.3 ng/mL for N-desmethyl ponatinib, 0.5 ng/mL for N-desmethyl imatinib, bosutinib, and ponatinib, and 2.5 ng/mL for imatinib and nilotinib. Within-batch and batch-to-batch precision at the lower limit of quantification and quality control levels were within 14.3% and 10.9%, respectively. Within-batch and batch-to-batch accuracies ranged from 15.5% to 13.0% and 5.70% to 7.03%, respectively. A positive electrospray ionization mode was used with a run time of 6.0 minutes. The assay applicability was verified by the successful measurement of 78 clinical samples from patients undergoing CML therapy. The method allows assessment of trough concentrations of TKIs and active metabolites in patients with CML, and hence can be used to assess blood samples in routine clinical settings.

Determination of polypeptide antibiotics in animal tissues using liquid chromatography tandem mass spectrometry based on in-line molecularly imprinted solid-phase extraction

Effective purification and enrichment of polypeptide antibiotics in animal tissues is always a challenge, due to the co-extraction of other endogenous peptides which usually interfere their final determination. In this study, a molecularly imprinted column was prepared by packing polymyxin E-imprinted particles into a 100 mm × 4.6 mm i.d. HPLC column. The as-prepared imprinted columns were able to tolerate 100% aqueous phase and exhibited good stability and high column efficiency. Polypeptides antibiotics with similar molecular size or spatial structure to polymyxin E were well retained by the imprinted column, suggesting class selectivity. After optimization of mobile phase conditions of imprinted column, polypeptide antibiotics in animal tissue extracts were enriched and cleaned up by in-line molecularly imprinted solid-phase extraction, allowing the screening of target analytes in complex samples at low concentration levels by UV detection. Eluate fraction from the imprinted column was collected, and further dried and re-dissolved with methanol-0.5% formic acid aqueous solution (80:20, v/v) for final LC-MS/MS analysis. Analysis was accomplished using multiple reaction monitoring (MRM) in positive electrospray ionization mode and analytes quantified using the matrix-matched external calibration curves. The results showed high correlation coefficients for target analytes in the linear range of 2 ∼ 200 μg kg−1. At four different concentration levels (limit of quantification, 50, 100 and 200 μg kg−1), recoveries of four polypeptide antibiotics in swine, cattle and chicken muscles ranged from 66.7 to 94.5% with relative standard deviations lower than 16.0%. The limits of detection (LOD) were 2.0 ∼ 4.0 μg/kg, depending upon the analyte and sample. Compared with a conventional pretreatment method, the imprinted column was able to remove more impurities and to significantly reduce matrix effects, allowing the accurate analysis of polypeptide antibiotics.

Determination of ceftriaxone in human plasma using liquid chromatography-tandem mass spectrometry.

Ceftriaxone is a cephalosporin antibiotic drug used as first-line treatment for a number of bacterial diseases. Ceftriaxone belongs to the third generation of cephalosporin and is available as an intramuscular or intravenous injection. Previously published pharmacokinetic studies have used high-performance liquid chromatography coupled with ultraviolet detection (HPLC-UV) for the quantification of ceftriaxone. This study aimed to develop and validate a bioanalytical method for the quantification of ceftriaxone in human plasma using liquid chromatography followed by tandem mass spectrometry (LC-MS/MS). Sample preparation was performed by protein precipitation of 100 µl plasma sample in combination with phospholipid-removal techniques to minimize matrix interferences. The chromatographic separation was performed on an Agilent Zorbax Eclipse Plus C18 column with 10 mM ammonium formate containing 2% formic acid: acetonitrile as mobile phase at a flow rate of 0.4 ml/min with a total run time of 10 minutes. Both the analyte and cefotaxime (internal standard) were detected using the positive electrospray ionization (ESI) mode and selected reaction monitoring (SRM) for the precursor-product ion transitions m/z 555.0→396.1 for ceftriaxone and 456.0→324.0 for cefotaxime. The method was validated over the concentration range of 1.01-200 μg/ml. Calibration response showed good linearity (correlation coefficient > 0.99) and matrix effects were within the ±15% limit in 6 different lots of sodium heparin plasma tested. However, citrate phosphate dextrose plasma resulted in a clear matrix enhancement of 24% at the low concentration level, which was not compensated for by the internal standard. Different anticoagulants (EDTA, heparin and citrate phosphate dextrose) also showed differences in recovery. Thus, it is important to use the same anticoagulant in calibration curves and clinical samples for analysis. The intra-assay and inter-assay precision were less than 5% and 10%, respectively, and therefore well within standard regulatory acceptance criterion of ±15%.

Development and Validation of the HPLC Method for Quantification of the Innovative Drug DD217, Factor Xa Inhibitor, in Rat Plasma for a Pharmacokinetic Study

Introductio n . Nowadays, discovery and development of innovative drugs represent a relevant goal for the pharmaceutical market. One of such drugs is N-(5-chloropyridine-2-yl)-2-({4-[ethanimidoyl(methyl)benzoyl}amino)-5-methylbenzamide hydrochloride (hereinafter DD217), an innovative drug that belongs to the class of anticoagulants, namely factor Xa inhibitors. Aim. The aim of this study was to develop and validate a method for DD217 determination in rat plasma by means of high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) to carry out pharmacokinetic studies. Materials and methods. Outbred Wistar rats were used in the study. Rats received a single dose of DD217 substance solution intragastrically at a dose of 5, 15, 30 mg/kg. The validated HPLC-MS/MS method was employed for DD217 determination in rat plasma. Nebivolol was chosen as the internal standard of the method. Chromatographic separation involved the use of Phenomenex Luna С8 column (3 µm, 50 × 4.6 mm) and gradient elution with water-acetonitrile solution containing 0.1 % formic acid. The total run time of each sample was equal to 2.0 min. DD217 and nebivolol were detected in positive electrospray ionization mode, the ion transitions monitored were m/z 436,1 → 119,9 and 406,0 → 151,0, respectively. Pharmacokinetic parameters and descriptive statistics were calculated through model-independent method in IBM SPSS Statistics v27 and Julia v1.6.0 (MixedModels v3.8.0, ClinicalTrialUtilities v0.5.1) software. Results and discussion. Method was validated by linearity, lower limit of quantification, selectivity, accuracy and precision, dilution integrity, matrix effect, recovery, carry-over, and stability. The lower limit of quantification of DD217 in rat plasma was 2.0 ng/mL. The method was successfully applied for establishing the pharmacokinetic parameters of DD217 substance in rat plasma after intragastric administration at a dose of 5, 15, 30 mg/kg. Conclusion. HPLC-MS/MS method for DD217 determination in plasma was developed, validated and applied in order to evaluate pharmacokinetic parameters of DD217 substance in rat plasma.

Effects of vindoline on rat cytochrome P450 isoform activities in vitro.

A specific ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) method has been described for the simultaneous determination of the metabolites of tacrine, bupropion, diclofenac, dextromethorphan and midazolam, which are the five probe drugs of the five cytochrome P450 (CYP450) isoforms CYP1A2, CYP2B, CYP2C11, CYP2D1 and CYP3A4. The inhibition degree was determined by calculating the IC50 . The chromatographic separation was performed on a C18 column with a mobile phase consisting of 0.1% formic acid and acetonitrile. The mass spectrometric analysis was conducted in positive electrospray ionization mode. The IC50 values of CYP1A2, CYP2B, CYP2C11, CYP2D1 and CYP3A were 113.4, 83.78, 22.50, 9.081 and 52.76 μmol L-1 , respectively. The in vitro results demonstrated that vindoline could inhibit CYP2D1 activity in rats, and weak inhibitory effect on CYP2C11 and CYP3A, but had no obvious effects on CYP1A2 and CYP2B.

Multi-residue analysis of 206 pesticides in grass forage by the one-step quick, easy, cheap, effective, rugged, and safe method combined with ultrahigh-performance liquid chromatography quadrupole orbitrap mass spectrometry.

A novel method for detecting pesticide multi-residue in grass forage (alfalfa and oat) was established based on the one-step automatic extractionand purification technology of quick, easy, cheap, effective, rugged, and safe combined with ultrahigh-performance liquid chromatography quadrupole Orbitrap high-resolution mass spectrometry. The crushed sample was extracted with acetonitrile with 1% acetate, followed by a cleanup step with a primary-secondary amine, octadecylsilane, and graphitized carbon black. The extraction and purification were carried out using the one-step automatic pretreatment equipment. The target pesticides were acquired in positive ion electrospray ionization mode and full scan/data dependent secondary scan mode. The calibration curve shows good linearity over the corresponding concentration range, with the coefficient of determination greater than 0.99. The screening detection limits were 0.5-50μg/kg, and the limit of quantification for the 206 pesticides was set at 1-50μg/kg. At the spiking levels of one, two, and 10 times of limit of quantification, more than 95% of pesticides had recovery between 70-120%, with a relative standard deviation ≤20%. The method was proved to be simple, rapid, high-sensitivity, and could be routinely used for the high throughput screening and quantitative analysis of pesticide residues in alfalfa and oat.

Determination of acetochlor and its metabolites in urine using liquid chromatography-tandem mass spectrometry

Objective: A method for the determination of acetochlor and its metabolites in urine by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established. Methods: After cleaned-up by a HLB extraction cartridges, the urine was eluted with 1% acetic acid acetonitrile solution. The target compounds were separated by ACQUITY UPLC®HSS T3 Column (2.1 mm×100 mm×1.8 μm) by using 1% formic acid solution and acetonitrile as mobile phase with gradient elution program, and analyzed in positive electrospray ionization mode by liquid chromatography tandem mass spectrometry. Results: All the target compounds showed good linear relationships in the range of 1-50 μg/L, and the correlation coefficients (r) were higher than 0.997. The recoveries rates at three different spiked levels for all target compounds in blank matrices were 107.6%-129.1%, and the relative standard deviations (RSD) were 1.5%-9.9% (n=6) . The limits of detection and quantitation of the method were 0.04-0.11 μg/L and 0.15-0.42 μg/L, respectively, and target substances were detected in all urine samples from occupational exposure workers to acetochlor. Conclusion: This method is suitable for rapid screening and analysis of acetochlor and metabolites in urine with the advantages of accuracy, rapidity, simplicity, high sensitivity and good specificity.

Development and validation of a high performance liquid chromatography-MS/MS method for determination of SOMCL-15-290 in a first-in-human study.

Background: SOMCL-15-290 is a novel inhibitor that targets FGF receptor, CSF1 receptor and VEGF receptor (kinase insert domain receptor). Aim: This study was aiming at developing a specific high performance liquid chromatography-MS/MS method for quantifying SOMCL-15-290 in human plasma and supporting the first-in-human study. Methods: Plasma samples were prepared using the protein precipitation method and separated on a C18 110A column with acetonitrile and 0.2% formic acid solution as mobile phases. Quantification of SOMCL-15-290 was operated on an Xevo-TQS triple quadrupole tandem mass spectrometer in electrospray ionization positive mode. Results & conclusion: The validated determination method of SOMCL-15-290 has proved feasible and was successfully utilized in the first-in-human study of SOMCL-15-290 in advanced solid tumor patients.

LC‐MS based urine metabolomic profiling indicate altered gut microbiome and host lipid metabolites in Parkinson’s disease

Evidence indicates that host and gut microbial metabolism are dysregulated prior to the onset of motor symptoms, in the prodromal phase of Parkinson’s disease (PD). There is currently no definitive test for the diagnosis of Parkinson’s disease; this represents an urgent, unmet medical need to enable the effectiveness of current and future therapeutic interventions for PD. The aim of this study was to understand changes in host and microbial metabolism in PD patient biofluids which could reflect a transition from the healthy to diseased state. We performed a comprehensive untargeted metabolomics analysis of urinary lipid metabolites together with altered metabolites associated with the gut microbiota. A total of 64 urine samples consisting of 31 from age matched healthy controls and 33 from PD patients were used in this study. Samples were deproteinized and analysed by reverse phase (RP)/UPLC‐MS/MS methods with positive and negative ion mode electrospray ionization (ESI) and HILIC/UPLC‐MS/MS with negative ion mode ESI. 14 lipid metabolites were significantly altered in PD patients. Five metabolites were associated with bile acid metabolism and nine were from the cholesterol pathway. Changes in secondary bile acid metabolism, particularly secondary bile acids indicative of microbial metabolism changes, were evident in PD patients, with 11 altered metabolites associated with the gut microbiota being significantly altered. Interestingly, several lipid metabolites that were altered in PD patients correlated with specific gut microbiome metabolites. Our results provide new insights into altered lipid metabolism and gut dysbiosis in PD, however, confirmation in a larger cohort would be needed.

Antioxidant and anti-diabetic activities of crude ethanolic extract from the banana inflorescence of musa (ABB group) namwa maliong

Background: Banana inflorescence is one of the edible parts of banana. It is well-known to have antioxidants and anti-diabetic potential health benefits. Methods: In this study, the banana inflorescence from Musa (ABB group) Namwa Mali-Ong was prepared using ethanol extraction and investigated for its biochemical compositions and biological activities. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, ferric reducing antioxidant power (FRAP), and 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging activity assays were performed. The phytochemical composition of the extract was analyzed using the ultra-high-performance liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (UHLC-ESI-QTOF/MS) technique. Additionally, the ability of the extract to stimulate glucose in C2C12 myotube was investigated. Results: The ethanolic extract of banana inflorescence contained carbohydrate, protein, phenolic, and flavonoid compounds. The results show that the extract exhibited low-level antioxidant activities. For example, the half-maximal inhibitory concentration (IC50) in the DPPH and ABTS assays was at 27.89 ± 0.054 and 21.33 ± 0.87 mg/mL, respectively. Although the extract possesses low-level antioxidant activities, it stimulated glucose uptake in C2C12 myotubes in a dose- and time-dependent fashion. Consistently, the LC-ESI-QTOF/MS analysis in both positive and negative electrospray ionization modes reveals several components in the extract such as phytosphingosine and α-linolenic acid that have previously been shown to exhibit an anti-diabetic activity.Conclusion: The results show that the inflorescence ethanolic extract possesses antioxidant and anti-diabetic activities and may potentially be developed into a health-promoting product such as an anti-diabetic drug. Keywords: antioxidant activity; banana inflorescence; glucose uptake; anti-diabetic; C2C12 myotubes

Spontaneous Water Radical Cation Oxidation at Double Bonds in Microdroplets.

Spontaneous oxidation of compounds containing diverse X=Y moieties (e.g., sulfonamides, ketones, esters, sulfones) occurs readily in organic-solvent microdroplets. This surprising phenomenon is proposed to be driven by the generation of an intermediate species [M+H2O]+·: a covalent adduct of water radical cation (H2O +· ) with the reactant molecule (M). The adduct is observed in the positive ion mass spectrum while its formation in the interfacial region of the microdroplet (i.e., at the air-droplet interface) is indicated by the strong dependence of the oxidation product formation on the spray distance (which reflects the droplet size and consequently the surface-to-volume ratio) and the solvent composition. Importantly, based on the screening of a ca. 21,000-compound library and the detailed consideration of six functional groups, the formation of a molecular adduct with the water radical cation is a significant route to ionization in positive ion mode electrospray, where it is favored in those compounds with X=Y moieties which lack basic groups. A set of model monofunctional systems was studied and in one case, benzyl benzoate, evidence was found for oxidation driven by hydroxyl radical adduct formation followed by protonation in addition to the dominant water radical cation addition process. Significant implications of molecular ionization by water radical cations for oxidation processes in atmospheric aerosols, analytical mass spectrometry and small-scale synthesis are noted.

Simultaneous determination of pyflubumide and its metabolite in vegetables and fruits by ultrahigh performance liquid chromatography-tandem mass spectrometry.

A rapid and cost-effective analytical method based on ultrahigh-performance liquid chromatography-tandem mass spectrometry was designed and verified for simultaneously monitoring the novel acaricide pyflubumide and its metabolite (pyflubumide-des(2-methyl-1oxopropyl)) in vegetables and fruits. After the extraction with acetonitrile, the samples were purified by dispersive solid-phase extraction with multi-walled carbon nanotubes. Detection of the two target analytes was achieved within 3.0min using a positive electrospray ionization mode. The average recovery, intra-day precision, and inter-day precision of the two analytes at three spiked levels (2, 20, and 100 μg/kg) were 75.0-101.0, 0.4-4.4, and 0.6-5.3%, respectively. The limit of quantification of two compounds was 2 μg/kg, which was far below the maximum residue limits of pyflubumide in foods established by Japan and South Korea. Finally, the concentrations of pyflubumide and its metabolite in the samples were 16.6 and 7.8 μg/kg respectively, which verified the practicability and reliability of the method. The method was used to efficiently detect pyflubumide and its metabolite in real samples and was confirmed to be robust and effective for routinely analyzing both pyflubumide and its metabolite in vegetable and fruit samples.