Ultra-performance Liquid Chromatography-tandem Research Articles

An Investigation of Pharmacokinetic Interaction of Vericiguat with Apigenin based on a Newly Developed Ultra-performance Liquid Chromatography-tandem Mass Spectrometry Assay.

Vericiguat, as a new stimulator of soluble guanylate cyclase (s- GC), was recently approved as a first-in-class treatment for reducing risks in patients with ejection fraction less than 45 percent and heart failure (HF) in the USA. The main aim of the present experiment was to establish an acceptable, sensitive assay based on ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) for quantitatively analyzing the plasma concentration levels of vericiguat in rats, and to further evaluate the effect of apigenin on the metabolism of vericiguat in vivo. In sample processes, acetonitrile was finally chosen for quickly precipitating protein. The levels of vericiguat in plasma were analyzed by a Xevo TQ-S triple quadrupole tandem mass spectrometry (Milford, MA, USA) in a positive ion mode. The scope of the calibration standard for vericiguat ranged from 0.5 to 1000 ng/mL, where a great linearity was acceptable. The lower limit of quantification (also called LLOQ) of vericiguat presented the sensitivity of this assay was evaluated as low as 0.5 ng/mL. Additionally, selectivity, accuracy and precision, extraction recovery, matrix effect, and stability were all verified. Subsequently, this approach also supported to assess the plasmatic concentrations of vericiguat from an interaction survey on herb-- drug, in which oral administration of apigenin (20 mg/kg) obviously increased the plasmatic levels of vericiguat and altered the pharmacokinetics of vericiguat in rats. These results would help us to further understand the pharmacokinetic properties of vericiguat when co-administration with apigenin, and to avoid unexpected clinical risks in the future.

Simultaneous determination of total homocysteine, methionine, methylmalonic acid and 2-methylcitric acid in dried blood spots by ultra-performance liquid chromatography–tandem mass spectrometry

Homocysteine, methionine, methylmalonic acid and 2-methylcitric acid are clinically relevant markers in the methionine, propionate, and cobalamin metabolism. This study aimed to develop and validate an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for simultaneously determining total homocysteine, methionine, methylmalonic acid and 2-methylcitric acid in dried blood spots. Three 3.2 mm discs were punched from each calibrator, quality control, and sample dried blood spot into a 96-well U-plate. Each sample was spiked with internal standards and extracted. Then the supernatant was transferred to another 96-well U-plate. After nitrogen drying, the dried residues were reconstituted, centrifuged, and the resulting supernatant was transferred to another 96-well plate for analysis. The method was performed using UPLC-MS/MS within 3 min, validated according to guidance documents, and applied to 72 samples from confirmed patients with methionine, propionate, and cobalamin metabolism disorders. The UPLC-MS/MS method provided satisfactory separation of the four analytes. The R2 values were ≥ 0.9937 for all analytes. The recoveries ranged from 94.17 to 114.29 %, and the coefficients of variation for intraday and interday precision were 0.19 % to 5.23 % and 1.02 % to 6.89 %, respectively. No significant carry-over was detected for the four analytes, and most of confirmed samples exhibited biomarker patterns characteristic of the relevant disorders. A simple and fast UPLC-MS/MS method was successfully developed, validated, and applied to clinical samples for the simultaneous determination of total homocysteine, methionine, methylmalonic acid, and 2-methylcitric acid in dried blood spots.

Steroid profiling for the diagnosis of congenital adrenal hyperplasia by microbore ultra-performance liquid chromatography–tandem mass spectrometry

BackgroundA rapid and accurate measurement approach for 17α-hydroxyprogesterone (17-OHP) and related steroids in amount/volume-limited clinic samples is of importance for precise newborn diagnosis of congenital adrenal hyperplasia (CAH) and its subtypes in clinic. MethodsSixteen steroids (17-OHP, androstenedione, cortisol, tetrahydro-11-deoxycortisol, pregnenolone, progesterone, 11-deoxycorticosterone, corticosterone, 21-deoxycortisol, 11-deoxycortisol, dehydroepiandrosterone, testosterone, aldosterone, 17α-hydroxypregnenolone, dihydrotestosterone and 18-hydroxycorticosterone) were included in the panel of high-throughput microbore ultra-performance liquid chromatography-tandem mass spectrometry. Samples were collected from 126 normal subjects and 65 patients including different subtypes of CAH. ResultsThe method was validated with satisfactory analytical performance in linearity, repeatability, recovery and limit of detection. Reference intervals for 16 steroids were established by quantifying the level of steroids detected in normal infants. The applicability of the method was tested by differentiating steroid metabolic characteristics between normal infants and infants with CAH, as well as between infants with different CAH subtypes. The relevance of 17-OHP, 21-deoxycortisol, and 17-OHP/11-deoxycortisol for 21-hydroxylase deficiency screening was demonstrated. The level of 11-deoxycorticosterone, 11-deoxycortisol, progesterone and androstenedione can be used for the diagnosis of different rare subtypes of CAH. ConclusionThis study provides a strategy for highly efficient steroid analysis of amount/volume-limited clinic samples and holds great potential for clinical diagnosis of CAH.

Quantification of vancomycin and clindamycin in human plasma and synovial fluid applying ultra-performance liquid chromatography tandem mass spectrometry

Periprosthetic joint infection is a challenging infection involving the joint prosthesis and adjacent tissue, such as synovial fluid, synovial tissue, and bone tissue. The current treatment consists of multiple surgical revisions and long-term antibiotic therapy. Treatment failure can cause poor functional outcome and reduced quality of life. Further research on the extent of antibiotic penetration into the infected tissues is of great importance. Our work aimed to develop and validate a novel ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the determination of the commonly administered antibiotics vancomycin and clindamycin in plasma and synovial fluid. An extraction procedure consisting of zinc sulfate precipitation and dilution with eluent was used for both analytes. Chromatographic separation was performed on a Waters Acquity UPLC HSS T3 C18 column (1.8 µm, 2.1 × 100 mm), and quantification was carried out by a Waters Xevo TQ-S micro mass spectrometer. Stable isotope-labeled vancomycin-d10 served as internal standard. The method validation was performed based on the guidelines of the EMA and FDA. The calibration curves were linear over the range of 0.5–50 mg/L, with a coefficient of determination above 0.990. The validation results for precision and accuracy, specificity, matrix effects and stability were all within the acceptance range. An accurate and rapid method for the simultaneous quantification of vancomycin and clindamycin in human plasma and synovial fluid on the UPLC-MS/MS was developed, optimized and validated. The analysis has a run time of 5.2 min and 50 µL sample volume is needed. This developed method was successfully applied in eight patients with PJI and is suitable to determine the exposure of antibiotics in plasma and synovial fluid in patients during current PK/PD studies.

Simultaneous Determination of Fourteen Marker Compounds in the Traditional Herbal Prescription, Geumgwesingihwan, Using Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Geumgwesingihwan (GSH) is a traditional herbal prescription composed of eight medicinal herbs: Rehmannia glutinosa (Gaertn.) DC., Dioscorea japonica Thunb., Cornus officinalis Siebold and Zucc., Poria cocos Wolf, Paeonia suffruticosa Andrews, Alisma plantago-aquatica subsp. orientale (Sam.) Sam., Achyranthes bidentate Blume, and Plantago asiatica L. This study developed and validated an ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method in the multiple reaction monitoring (MRM) mode for simultaneous determination of 14 compounds (allantoin, gallic acid, 5-(hydroxymethyl)furfural, geniposidic acid, oxypaeoniflorin, loganin, geniposide, paeoniflorin, ecdysterone, verbascoside, cornuside, benzoylpaeoniflorin, paeonol, and alisol B acetate) in GSH. The chromatographic separation of all marker analytes was carried out on an Acquity UPLC BEH C18 column (100 mm × 2.1 mm, 1.7 µm) using gradient elution of a mobile phase of distilled water–acetonitrile containing 0.1% acetic acid. The newly established UPLC–MS/MS MRM method was validated by evaluating the linearity, the limits of detection and quantification, recovery, and precision. All markers were detected at concentrations of 6.94–4126.28 mg/kg. In addition, the recovery was 76.65–119.49% and the relative standard deviation value of the precision was 0.19–9.91%. The newly developed and validated UPLC–MS/MS assay will provide useful information for quality assessment of GSH.

Development and validation of a ultraperformance liquid chromatography-tandem mass spectrometry method for quantifying free and total dabigatran in human plasma: An application for a bioequivalence study.

Dabigatran etexilate mesylate (DABE), a prodrug, quickly changes into dabigatran (DAB) after its oral administration. Accordingly, detecting DABE in plasma is practically unmanageable. An ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) technique was developed and validated to compute free DAB in participants. For the first time, the central composite design, a type of response surface methodology, was applied for optimizing variables affecting the cleavage of glucuronide bond. In addition, the pharmacokinetic parameters of generic medication (okanadab) were determined, and the obtained outcomes were compared with those of the branded drug (pradaxa). The sample preparation was done using methanol as a protein precipitant and the separation was achieved using an ACQUITY UPLC BEH C18 column (2.1 × 50 mm, 1.7 μm). The elution was isocratically conducted using 10mM ammonium formate:methanol (72:28, v/v) as a mobile phase and the flow rate was 0.25 mL/min. Multiple reaction monitoring and positive electrospray ionization were used. The determination was performed within 1min, and the calibration growth curve was established over a range of 1.19-475 ng/mL using DAB-d3 as a tagged internal standard. Bioequivalence research was validated following the US Food and Drug Administration (US FDA) guidelines for bioanalytical procedures and acceptable outcomes were achieved. The outcomes for okanadab and pradaxa did not differ significantly.

Rapid detection of α-amanitin and β-amanitin in rat plasma by ultra-performance liquid chromatography-tandem mass spectrometry and its application to the toxicokinetic study of Lepiota brunneoincarnata.

Lepiota brunneoincarnata is a well-known poisonous mushroom and is responsible for fatal mushroom poisoning cases worldwide. α-Amanitin and β-amanitin are the main amatoxin compounds of Lepiota brunneoincarnata. However, there are no published toxicokinetic studies of Lepiota brunneoincarnata. To study the toxicokinetics of Lepiota brunneoincarnata, we developed an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determination of α-amanitin and β-amanitin in rat plasma. UPLC-MS/MS analyses were performed with a triple quadrupole mass spectrometer in positive-ion mode. The sensitivity of α-amanitin and β-amanitin detection was increased by inhibiting the production of [M + Na]+ adducts. α-Amanitin and β-amanitin were separated and quantified on an UPLC octadecyl silyl column in only 2.5min. The linear ranges were 3.0-3000ng/mL for α-amanitin and 1.8-1800ng/mL for β-amanitin with a correlation coefficient r > 0.99 for both analytes. The lower limit of quantification of 3.0ng/mL for α-amanitin and 1.8ng/mL for β-amanitin was achieved using only 50 μL of rat plasma. The accuracy of α-amanitin and β-amanitin was between - 9.5 and 7.0% with the precision ranged from 2.2 to 12.5%. The developed method was then applied for Lepiota brunneoincarnata toxicokinetic study after intravenous administration of Lepiota brunneoincarnata extracts. Establishing UPLC-MS/MS method for quantifying amanitines in rat plasma successfully enabled toxicokinetic study of Lepiota brunneoincarnata extracts.

Determination of three Unsaturated Fatty Acids in Pressure Ulcer Rats Using A UPLC-MS/MS Method

Background:The serum levels of Docosahexaenoic Acid (DHA), Eicosapentaenoic Acid (EPA) and Arachidonic Acid (AA) under the state of Pressure Ulcers (PUs) are still unclear. Introduction:In order to investigate serum levels of DHA, EPA, and AA in PUs rats, an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS) method was developed and validated. Methods:Chromatographic separation of DHA, EPA, AA was carried out on a BEH C18 column and gradient elute consisted of 5 mM ammonium acetate-0.1% formic acid and acetonitrile. Subsequently, fifty rats were divided into five groups (n=10), four PU groups (A-D) underwent various pressure and release time protocols, with group E as the control. The concentrations of DHA, EPA, AA from five groups were determined by using a validated method. Results:The results showed there was good linearity for DHA (327.3/283.4), EPA (301.2/257.0), and AA (303.1/258.9) within 0.05-6.4 μg/mL. In control group, the levels of DHA, AA and EPA were 1.16±0.68, 0.59±0.19 and 0.78±0.21 μg/mL. At the end of modeling, concentrations of DHA, EPA and AA were increased after long and persistent pressure (>8 h). Especially, the level of DHA was significantly higher (P<0.01) than that of control group. Conclusion: A stable, rA stable, reliable and accurate UPLC-MS/MS for determination of DHA, EPA, AA in blood was developed. Serum concentrations of DHA, EPA and AA were altered differently after long and persistent pressure (>8 h), and DHA is a remarkable one.eliable and accurate UPLC-MS/MS for determination of DHA, EPA, AA in blood was developed. Serum concentrations of DHA, EPA and AA were altered differently after long and persistent pressure (>8 h), and DHA is a remarkable one.

Rapid determination of 20 bile acids in human serum by ultra performance liquid chromatography-tandem mass spectrometry.

A method was established for the simultaneous determination of 20 kinds of bile acids in human serum employing ultraperformance liquid chromatography-tandem mass spectrometry. Chromatographic conditions and sample preparation were optimized to achieve good separation and maximum sensitivity for these analytes. The linearity, accuracy and repeatability of the development method were validated with a series of experiments. Under the optimum conditions, good linearities were achieved in the quantitative range for each bile acid with the correlation coefficients (r2 ) >0.9901. The limit of detections (signal-noise ratio 3) of the method were in a range from 0.02 to 0.57 nmol/L. The recoveries were in the range of 88.1-109.9%, RSD < 6.12%. This method was successfully applied for the determination of bile acids in a human serum sample with simple operation, high sensitivity and good accuracy, and provides a reference for the clinical determination of bile acid content.

Ultra performance liquid chromatography–tandem mass spectrometry assay for the quantification of RNA and DNA methylation

Previous studies have reported that nucleic acid methylation is a critical element in cardiovascular disease, and most studies mainly focused on sequencing and biochemical research. Here we developed an Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS) method for the quantification analysis of the dissociative epigenetic modified nucleosides (5mdC, 5mrC, m6A) in Myocardial Infarction (MI) SD rats from different periods (1 week, 4 weeks, 8 weeks) after the surgery. The samples for analysis were obtained from heart tissue and blood of the rats. All the quantification results are compared with the sham-operated group. Total RNA and DNA were isolated by enzymatic hydrolytic methods before the UPLC-MS/MS analysis. The statistical analysis demonstrates the dynamic changes of modified nucleosides in MI rats, and it showed good specificity, accuracy, stability and less samples were needed in the method. In this paper, we discovered that the concentration of 5mdC, 5mrC, m6A from heart tissue significantly increased at 8 weeks after the surgery. Furthermore, UPLC-MS/MS helps us observe the similar change of the concentration of those 3 methylated biomarkers in peripheral blood after 8 weeks. The result shows that the dynamic process of those 3 methylated biomarkers in peripheral blood is related to the content of methylated biomarkers from the heart tissue. Based on the scientific evidence available, we proved that the methylation of genetic materials in peripheral blood is similar to myocardial infarction tissue. The relation between them indicates that peripheral blood could be a promising alternative to the heart tissue which monitor the level of methylation and MI diagnosis-aided.

Development and Validation of an Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry Method to Determine Maduramicin in Crayfish (Procambarus clarkii) and Evaluate Food Safety.

Maduramicin (MAD) is widely introduced into aquatic environments and results in the contamination of fish products. Worryingly, the consumption of MAD-contaminated crayfish (Procambarus clarkii) may induce symptoms of Haff disease. In this study, to monitor this potential contamination and to understand the residue and elimination characteristics of MAD in edible tissues of crayfish, a sensitive and efficient ultra-performance liquid chromatography–tandem mass spectrometry method was developed, validated, and applied. After extraction with acetonitrile and purification by solid-phase extraction column, multiple-reaction monitoring mass spectrometry with positive ionization mode was used to determine MAD’s residues. The limits of detection and of quantification were 6 μg·kg−1 and 20 μg·kg−1, respectively. The fortified recoveries ranged from 74.2% to 110.4%, with relative standard deviation of 1.2% to 10.1%. Furthermore, MAD was completely eliminated after 3 and 5 days from abdominal muscle and hepatopancreas tissues of crayfish, respectively. The maximum residue limits (MRLs) of MAD respectively was 200 μg·kg−1 in muscle and 600 μg·kg−1 in the hepatopancreas, and its withdrawal time in both edible tissues was 25.8 °C·d. Collectively, the results of this study indicate the proposed method is an efficient tool to evaluate the public health risk associated with crayfish consumption.

Determination of a novel photosensitizer sinoporphyrin sodium in human plasma by ultra-performance liquid chromatography–tandem mass spectrometry

Sinoporphyrin sodium (DVDMS) is a new photosensitizer (PS) and it is used in photodynamic therapy (PDT) against tumor. In this paper, a simple, rapid and specific ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the quantitation of DVDMS in human plasma was developed. The analytes were extracted from plasma samples using liquid-liquid extraction (LLE) after addition of testosterone (internal standard) and chromatographed on an AQUITY UPLC Protein BEH C4 column (50 × 2.1 mm, i.d. 1.7 μm) thermostatted at 40 °C with acetonitrile-water (0.1% formic acid and 0.1 mM K2EDTA) as the gradient mobile phase at flow rate of 0.5 mL/min. The detection was performed on an API 5500 mass spectrometer coupled with electrospray ionization (ESI) source in positive mode. The multiple reactions monitoring (MRM) transitions of m/z 1143.6→563.2 and m/z 289.3→109.1 were used to quantify DVDMS and IS, respectively. The assay was validated over the concentration range of 30−3000 ng/mL. Precision and accuracy are in accordance with the generally accepted criteria for bioanalytical methods. The extraction recovery and the matrix effect were investigated. This method was successfully applied to pharmacokinetic (PK) study of DVDMS in Chinese patients with solid tumor after treated with DVDMS-PDT for the first time.

Determination of N-[4- (4-aminobenzyl) -phenyl] acetamide hemoglobin adduct in blood by ultra performance liquid chromatography-tandem mass spectrometry

Objective: To establish the method for the determination of N-Acetyl-4, 4'-diaminodiphenylmethane (AcMDA) adduct in the hemoglobin by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) . Methods: The 20 mg hemoglobin sample was weighed into a 15 ml centrifuge tube, adding 20 μg/L internal standard solution AcMDA-D8 10 μl, then hydrolyzed with 1 ml 0.1 mol/L sodium hydroxide solution at 37°C for 0.5 hours, extracted with dichloromethane and concentrated by vacuum concentrator. The residue was dissolved in acetonitrile and detected by UPLC-MS/MS, then quantitative by internal standard method. Results: The linearity of the method was good at the range of 0.05-25.00 μg/L with a correlation coefficient of 0.9996, the detection limit (LOD) and limit of quantitation (LOQ) were 0.07 and 0.2 ng/g Hb, respectively. The recovery rate was ranged from 91.0%-95.4%; the relative standard deviation (RSD) of intra-and inter-batch precision were 4.5%-6.3% and 3.7%-4.4%, respectively. Conclusion: The determination method meet the requirement of GBZ/T 210.5-2008.

Development of a method of hollow fiber-based solid-phase microextraction followed by ultra performance liquid chromatography-tandem mass spectrometry for determination of five antipsychotics in human whole blood and urine

This work focused on the development and validation of a method based on hollow fiber-based solid-phase microextraction coupled to ultra-performance liquid chromatography tandem mass spectrometry (HF-based-SPME-UPLC-MS/MS) for the determination of five antipsychotics at a pg mL–1 level in human whole blood and urine. Four types of hollow fiber membrane materials, including polyether sulfone, polypropylene, polyvinyl chloride and polyvinylidene fluoride were investigated. Finally, polyether sulfone hollow fiber without any modification was selected as the adsorption medium for solid-phase microextraction (SPME) with the following extraction procedure: the analytes were adsorbed onto the hollow fiber in the sample bottle with application of ultrasonication. Subsequently, the hollow fiber was transferred into a slim glass tube containing an appropriate solvent, and the analytes were desorbed by ultrasound treatment before detection by UPLC-MS/MS. In order to obtain satisfactory extraction efficiency, extraction parameters such as hollow fiber membrane material, pH, hollow fiber length, extraction time, desorption solvent and desorption time were investigated. Under the optimum experimental conditions, this method allowed for determination of five antipsychotics in human whole blood with excellent limits of quantification (LOQs) (25.0, 12.5, 25.0, 25.0 and 12.5 pg mL–1 for perphenazine, chlorpromazine, chlorprothixene, promethazine and trifluoperazine, respectively). The corresponding LOQs in human urine were 25.0, 12.5, 12.5, 12.5 and 12.5 pg mL–1 for the respective antipsychotics. The precision (RSD) was no more than 13.3%. The extraction recoveries for human whole blood and urine were in the range of 46.4–96.6% and 65.2–101.9%, respectively. The proposed method was compared with other methods from the literature and the results demonstrate that it is a simple, sensitive, efficient and green technique. It is suitable for analyzing trace target analytes in complex matrices such as biological samples and can provide a reliable tool for drug monitoring especially in forensic analysis and case of drug abuse.

Chemistry of Autumn Colors: Quantitative Spectrophotometric Analysis of Anthocyanins and Carotenoids and Qualitative Analysis of Anthocyanins by Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry.

The autumnal leaf color change is a familiar phenomenon to most students living in temperate climate zones. The extraction and analysis of the pigments of the autumn leaves provide an engaging way to study the phenomenon utilizing both simple as well as more sophisticated analytical methods. In this laboratory experiment, students extract the red and yellow pigments, that is, anthocyanins and carotenoids from leaves and separate them from each other by liquid–liquid extractions. From the separated phases, anthocyanin and carotenoid concentrations can be evaluated visually or spectrophotometrically. The anthocyanins are analyzed by a rapid and simple ultra-performance liquid chromatography–tandem mass spectrometry method to discover which of the six most common groups of anthocyanins are present in the sample. The simplicity of the experiment setup allows it to be used as an introduction to mass spectrometry since the results can be easily interpreted without complicated data processing. The experiment provides opportunities for learning outside the classroom, as the samples can be collected from the nearby parks or forests and analyzed using more sophisticated methods on a student visit to a university or other research institution. The sample preparation followed by the visual analyses of the phases is however simple enough to be performed in a regular school laboratory.

Development and Validation of UPLC-ESI-MS/MS Technique for the Determination of 2-Isopropyl-4-(chloromethyl)thiazole in Ritonavir

The objective of this work was to develop and validate a rapid, highly sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-ESI-MS/MS) method for the quantification of 2-isopropyl-4-(chloromethyl)thiazole in ritonavir. Chromatographic conditions of this impurity were achieved on an AQUITY UPLC column HSS (high strength silica) T3 column (100 mm long, 2.1 mm internal diameter, 1.8 μm diameter) using a gradient elution with 0.1% formic acid in water and methanol at a flow rate of 0.3 mL/min. LCMS/MS was operated under the multiple reaction mode (MRM) using electrospray ionization technique in positive ion mode and the transitions of m/z 176.1[M+H]+→140.1 for quantifier, 176.1[M+H]+→71.0 for qualifier were used to measure the impurity, respectively. The total chromatographic run time was 10 min. Full validation of the analytical method was carried out, including its system precision, selectivity, linearity, accuracy, recovery, ruggedness, stability and robustness. A linear response function was achieved in the concentration range of 0.12-1.86 μg/g with r &gt; 0.99. The detection limit and quantitation limit of this impurity were 0.06 and 0.12 μg/g, respectively. Consistent recoveries were obtained during intra- and inter-day precision experiments in validation ranged from 80-120%. The developed method could be helpful not only for quality control and also for risk management of potential genotoxicity of this impurity in ritonavir drug substance.

8-Hydroxyguanosine as a possible RNA oxidative modification marker in urine from colorectal cancer patients: Evaluation by ultra performance liquid chromatography-tandem mass spectrometry

Oxidative RNA damage has been found to be associated with a variety of diseases, and 8-hydroxyguanosine (8-OHG) is a typical marker of oxidative modification of RNA. This guanosine modification is an emerging biomarker for disease detection and determination of 8-OHG in human urine is favored because it is noninvasive to patients. However, due to its poor ionization efficiency in mass spectrometry and trace amount in urine, accurate quantification of this modified nucleoside is still challenging. Herein, a rapid, accurate, sensitive and robust method using solid-phase extraction (SPE) combined with isotope dilution ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed for detection of this oxidative RNA modification in human urine. The limit of detection can reach 1.5 fmol and the method exhibits good precision on intra-day (1.8–3.3%) and inter-day (0.6–1.2%) analyses. Satisfactory recovery (87.5–107.2%) at three spiked levels was achieved by using HLB cartridge for urine pretreatment. Using this method, we quantified 8-OHG in urine from 65 colorectal cancer (CRC) patients and 76 healthy volunteers. The measured level of urinary 8-OHG for CRC patients and healthy controls is 1.91 ± 0.63 nmol/mmol creatinine and 1.33 ± 0.35 nmol/mmol creatinine, respectively. We found the content of 8-OHG in urine was raised in CRC patients patients, implying this oxidative RNA modification marker could act as a potential noninvasive indicator for early screening of CRC. In addition, this study will make contributions to the investigations of the influences of oxidative stress on the formation and development of CRC.

High dietary glycemic load is associated with higher concentrations of urinary advanced glycation endproducts: the Cohort on Diabetes and Atherosclerosis Maastricht (CODAM) Study

Advanced glycation endproducts (AGEs) and their precursors (dicarbonyls) are associated with the progression of diseases such as diabetes and cardiovascular disease. Plasma concentrations of dicarbonyls methylglyoxal (MGO), glyoxal (GO), and 3-deoxyglucosone (3-DG) are increased after an oral glucose load indicating that consumption of diets high in carbohydrates may induce the endogenous formation of dicarbonyls and AGEs. To examine the associations of dietary glycemic index (GI) and glycemic load (GL) with concentrations of dicarbonyls and AGEs in plasma and urine. Cross-sectional analyses were performed in a human observational cohort [Cohort on Diabetes and Atherosclerosis Maastricht (CODAM), n=494, 59±7 y, 25% type 2 diabetes]. GI and GL were derived from FFQs. Dicarbonyls and AGEs were measured in the fasting state by ultra-performance liquid chromatography-tandem MS. MGO, GO, and 3-DG and protein-bound Nε-(carboxymethyl)lysine (CML), Nε-(1-carboxyethyl)lysine (CEL), and pentosidine were measured in plasma. Free forms of CML, CEL, and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) were measured in both plasma and urine. Multiple linear regression was performed with dicarbonyls and AGEs as dependent variables, and dietary GI or GL as main independent variables (all standardized). Models were adjusted for health and lifestyle factors, dietary factors, and reciprocally for GI and GL. As this was an explorative study, we did not adjust for multiple testing. GI was not associated with any of the dicarbonyls or AGEs. GL was positively associated with free urinary MG-H1 (β=0.34; 95% CI: 0.12, 0.55). Furthermore, GL was positively associated with free plasma MG-H1 and free urinary CML (β=0.23; 95% CI: 0.02, 0.43; and β=0.28; 95% CI: 0.06, 0.50), but these associations were not independent of dietary AGE intake. A habitual diet higher in GL is associated with higher concentrations of free urinary MG-H1. This urinary AGE is most likely a reflection of AGE accumulation and degradation in tissues, where they may be involved in tissue dysfunction.

Application and enantioselective residue determination of chiral pesticide penconazole in grape, tea, aquatic vegetables and soil by ultra performance liquid chromatography-tandem mass spectrometry

Penconazole is a typical triazole fungicide with wide use on fruits, vegetables, and tea plants to control powdery mildew. In the present study, an efficient graphite carbon black solid phase extraction (GCB-SPE) purification combined with chiral ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for determination of penconazole enantiomers in different complex matrices, including grape, tea, soil, lotus root, lotus leaf, lotus seed and hulls. The method was then applied to investigate the enantioselective dissipation of penconazole enantiomers in a real field experiment of grape and soil. As a result, a satisfactory separation of penconazole enantiomers on a chiral Lux Cellulose-2 column (150 mm × 2 mm i.d., 3 µm) was obtained with 0.1% formic acid in methanol and 10 mmol L−1 ammonium acetate in water (75/25, v/v) as mobile phase at 0.25 mL min−1. The enantiomer (+)-penconazole was firstly eluted, and (-)-penconazole was then eluted. The method showed reliable performances in linearity, recovery and precision, the recoveries of (+)-penconazole and (-)-penconazole in all of six matrices were between 70.5% and 121.0% with the relative standard deviations (RSDs) ranging from 0.8% to 23.6% at the low, medium and high spiked levels. The limits of quantitation (LOQs) of this method were lower than 0.0025 mg kg−1 in grape, soil and lotus root, 0.005 mg kg−1 in lotus leaf, lotus seed meat and lotus seed shell, and 0.0125 mg kg−1 in tea. Results of field trials indicated that (-)-penconazole degraded faster than its (+)-isomer in grape. While only a moderate stereoselectivity was observed in soil, with (-)-penconazole preferential degraded. The proposed method could be used to investigate enantioselective environmental behavior of penconazole enantiomers in complex matrices. And results in this study could provide useful information on realistic risk assessment of penconazole in grape.

Determination of Ethinyl Estradiol and Levonorgestrel in Human Plasma with Prednisone as Internal Standard Using Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry.

Objective:Ethinyl estradiol and levonorgestrel as a combination of oral contraceptive drugs have very low dosage levels; hence, a highly sensitive and selective method of using ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) is needed.Materials and Methods:This method was developed using prednisone as an internal standard, thus the purpose of this research was to get the optimum condition. The analytical method had been fully validated according to the European Medicines Agency guidelines, 2011. A reverse-phase chromatography separation was performed on ACQUITY UPLC ethylene bridged hybrid C18 column (1.7 μm, 2.1 × 50mm), eluted at a 0.3 mL/min flow rate under a gradient of mobile phase of 0.1% formic acid in water and acetonitrile within 5 min. Sample preparation used protein precipitation followed by liquid–liquid extraction. Quantification analysis was performed by a triple quadrupole mass spectrometry with electrospray ionization in positive-ion mode. The multiple reaction monitoring was set at m/z: 530.16 → 171.08 for ethinyl estradiol derivatized by dansyl chloride; m/z: 313.16 → 245.10 for levonorgestrel; and m/z: 359.10 → 147.04 for prednisone.Results:The validated method was accurate, precise, and sensitive with a lower limit of quantification at 5 and 100 pg/mL for ethinyl estradiol and levonorgestrel, respectively.