UPLC-QTOF MS Research Articles

Metabolomics-Based Clinical Efficacy and Effect on the Endogenous Metabolites of Tangzhiqing Tablet, a Chinese Patent Medicine for Type 2 Diabetes Mellitus with Hypertriglyceridemia.

Tangzhiqing tablet (TZQ) is derived from Tangzhiqing formula, which has been used to regulate glucose and lipid metabolism in China for hundreds of years. However, as a new Chinese patent medicine, its clinical indication is not clear. To explore the clinical indication and effect on the patients with type 2 diabetes mellitus (T2DM), a pilot clinical trial and metabolomics study were carried out. In the clinical study, T2DM patients were divided into three groups and treated with TZQ, placebo, or acarbose for 12 weeks, respectively. The metabolomic study based on UPLC Q-TOF MS was performed including patients with hypertriglyceridemia in TZQ and placebo groups and healthy volunteers. The clinical results showed that TZQ could reduce glycosylated hemoglobin (HbA1c) and fasting insulin. For patients with hypertriglyceridemia in TZQ group, the levels of HbA1c all decreased and were correlated with the baseline level of triglyceride. Metabonomics data showed a significant difference between patients and healthy volunteers, and 17 biomarkers were identified. After 12-week treatment with TZQ, 11 biomarkers decreased significantly (p<0.05), suggesting that TZQ could improve the metabolomic abnormalities in these participants. In conclusion, the clinical indication of TZQ was T2DM with hypertriglyceridemia, and its target was related to glycerophospholipid metabolism.

UPLC-QTOF MS-Based Serum Metabolomic Profiling Analysis Reveals the Molecular Perturbations Underlying Uremic Pruritus.

As one of the most troublesome complications in patients with chronic renal disease, the etiology of uremic pruritus remains unknown, and the current therapeutic approaches are limited and unsatisfactory. To identify potential biomarkers for improving diagnosis and treatment and obtain a better understanding of the pathogenesis of uremic pruritus, we compared serum metabolome profiles of severe uremic pruritus (HUP) patients with mild uremic pruritus (LUP) patients using ultraperformance liquid chromatography-quadruple time-of-flight mass spectrometry (UPLC-QTOF MS). Partial least squares discriminant analysis (PLS-DA) showed that the metabolic profiles of HUP patients are distinguishable from those of LUP patients. Combining multivariate with univariate analysis, 22 significantly different metabolites between HUP and LUP patients were identified. Nine of the 22 metabolites in combination were characterized by a maximum area-under-receiver operating characteristic curve (AUC = 0.899) with a sensitivity of 85.1% and a specificity of 83.0% distinguishing HUP and LUP. Our results indicate that serum metabolome profiling might serve as a promising approach for the diagnosis of uremic pruritus and that the identified biomarkers may improve the understanding of pathophysiology of this disorder. Because the 9 metabolites were phospholipids, uremic toxins, and steroids, further studies may reveal their possible role in the pathogenesis of uremic pruritus.

Determination of multiple mycotoxins in feedstuffs by combined use of UPLC–MS/MS and UPLC–QTOF–MS

In this report, a UPLC–ESI–MS/MS method for the simultaneous determination of aflatoxins, ochratoxin A, zearalenone, deoxynivalenol, fumonisins, T-2 and HT-2 toxins, fusarenone X, diacetoxyscirpenol, and 3- and 15-acetyldeoxynivalenol in feedstuffs was developed. A quadrupole-time-of-flight mass spectrometer detector (QTOF–MS) operating in full scan mode was combined with the UPLC–ESI–MS/MS system to confirm the identity of detected mycotoxins and to identify other possible microbial metabolites occurring in samples. Sixty-two feed samples from the Spanish market were analyzed. Extraction of metabolites was carried out with acetonitrile-water-formic acid (80:19:1, v/v/v). Method detection and quantification limits and performance criteria set by Commission Regulation (EC) No 401/2006 were fulfilled. Relatively high levels of the main regulated mycotoxins and presence of non-regulated mycotoxins in feed samples were found. This is the first study in which mycotoxins and other microbial metabolites occurring in feed are studied using a UPLC–QTOF–MS system being therefore a reference report.

Degradation of phenylethanoid glycosides in Osmanthus fragrans Lour. flowers and its effect on anti-hypoxia activity

This study was aimed at investigating the chemical stability (the thermal, light and pH stability) of phenylethanoid glycosides (PhGs) in Osmanthus fragrans Lour. flowers, identifying the degradation products of acteoside and salidroside (major PhGs in O. fragrans flowers) by UPLC–QTOF–MS and studying the anti-hypoxia activity of PhGs after degradation. The degradation of PhGs followed first-order reaction kinetics, and the rate constant of acteoside (4.3 to 203.4 × 10−3 day−1) was higher than that of salidroside (3.9 to 33.3 × 10−3 day−1) in O. fragrans flowers. Salidroside was mainly hydrolyzed to tyrosol during storage, and the degradation products of acteoside were verbasoside, caffeic acid, isoacteoside, etc. In a model of cobalt chloride (CoCl2)-induced hypoxia in PC12 cells, the anti-hypoxia ability of PhGs decreased after degradation, which resulted from the reduction of PhGs contents. Particularly, caffeic acid exhibited stronger anti-hypoxia ability than acteoside and could slightly increase the anti-hypoxia ability of degraded acteoside. The results revealed that high temperature, high pH and light exposure caused PhGs degradation, and thus the anti-hypoxia ability of PhGs reduced.

Research on the neuro-protective compounds in Terminalia chebula retz extracts in-vivo by UPLC–QTOF-MS

We have developed a strategy to analyze the components absorbed in the plasma and brain tissue of rats after intragastric administration of Terminalia chebula Retz extracts by ultra-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC–QTOF-MS). Nine components (gallic acid, methyl gallate, ferulic acid, ethyl gallate, brevifolin carboxylic acid, ellagic acid, galloflavin, arjugenin, and arjunic acid) and four metabolites were identified in plasma, and five components (ethyl gallate, brevifolin carboxylic acid, ellagic acid, arjugenin, and arjunic acid) were identified in the rat brain based on their fragmentation behaviors. The components present in the plasma were associated with the antioxidant activity of T. chebula Retz, and the components absorbed in the brain were associated with its neuro-protective effects. This approach allowed us to rapidly determine the active components of T. chebula Retz and develop a method for its quality control. This analysis method showed good resolution and high sensitivity, and is a potentially powerful tool for the determination of effective components of natural products.

GENOMICS AND IMAGING DATA INFORMED METABOLOMICS: A BIOCHEMICAL ROADMAP FOR ALZHEIMER DISEASE

Increasing evidence supports that Alzheimer disease (AD) is a metabolic disease with high diabetes co-morbidity and a wide range of metabolic perturbations occurring early in the disease process. While genetic risk clearly plays a role in AD, the gut microbiome, exposome and diet also exert influences on brain metabolic health. Advances in analytical chemistry enable simultaneous measurement of 1000's of metabolites that can be integrated into tissue-specific metabolic networks enabling a new kind of metabolic systems analysis of AD and where peripheral and central metabolic changes can be connected. We will highlight developments in the metabolomics field and large initiatives within Accelerated Medicine Partnership (AMP-AD) and MOVE AD where metabolomics data is being generated and informed by genomics and imaging data. Fasting baseline serum samples from Alzheimer's Disease Neuroimaging Initiative ADNI1 (199 CN, 356 LMCI and 175 AD participants) were analyzed using targeted (AbsoluteIDQ-p180 and Biocrates Bile Acid Kit) and non-targeted metabolomics and lipidomics platforms (UPLC-TOF MS; UPLC-QTOF MS). ADNI GO/2 (150 CN, 100 SMC, 100 EMCI, 150 LMCI, and 150 mild AD) and Rotterdam studies were used for validation of findings. Partial correlation networks revealed changes in sphingomyelins and ether-containing phosphatidylcholines in preclinical biomarker-defined AD stages providing mechanistic insights about abeta and tau pathology and pointing to changes in membrane structure and function. Subsequent changes in acylcarnitines and several amines, including the branched chain amino acid valine and α-aminoadipic acid correlated with imaging changes and cognitive decline pointing to a role of mitochondrial energetics. Several metabolic changes related to liver enzymatic functions and gut microbiome activity correlated with imaging and cognitive changes highlighting a possible role for gut liver brain axis in disease pathogenesis. Meta-analysis across metabolomics studies reveals common biochemical findings when evaluated within a metabolic network context. Metabolomics identified key disease-related metabolic changes and disease-progression-related changes some related to liver and gut microbiome activity. Defining metabolic changes during AD disease trajectory and its relationship to clinical phenotypes provides a powerful roadmap for drug and biomarker discovery. Genomics and imaging data inform metabolomics data and together they provide a powerful systems approach for the study of AD.

Sphingolipids Profiling of Plasma in Patients with Diabetes Mellitus Associated with Atherosclerosis by a Novel Normal-Phase UPLC-QToF MS Method

A novel normal-phase UPLC-QToF MS method was developed for sphingolipids analysis, which was then applied to separate and identify seven classes of sphingolipids in plasma. The time-consuming of this novel method was much shorter than previous 2D LC–MS method, while the sensitivity, repeatability and resolution for sphingolipids analysis were better or comparable. Besides, the differences of lipids in human plasma among diabetes mellitus patients, diabetes mellitus associated with atherosclerosis patients and control subjects were also compared. Finally, 12 sphingolipids species were identified as the amounts of which in diabetes mellitus associated with atherosclerosis patients were significantly higher than them in diabetes mellitus patients (VIP >1.0, p value 1.5). As the isomers of GalCs and GluCs were successfully separated, it was found that five GluCs, rather than GalCs, were included in these 12 potential biomarkers. These results suggest the need to separate GalCs from GluCs, and also indicated that there may be some extra activation pathways of diabetes mellitus associated with atherosclerosis, different from the atherosclerosis pathway and the diabetes mellitus pathway, causing cardiovascular disease.

Fabric phase sorptive extraction as a reliable tool for rapid screening and detection of freshness markers in oranges

A simple, fast and sensitive analyte extraction method based on fabric phase sorptive extraction (FPSE) followed by gas chromatography-mass spectrometry (GC–MS) and ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC–QTOF–MS) analysis was developed for the analysis of 12 volatile compounds that represent most of the principal chemical families possessing different polarities and volatilities. Five FPSE media coated with different sol-gel sorbent chemistries having different polarities and selectivities were studied: long chain poly(dimethylsiloxane) (PDMS), short chain poly(tetrahydrofuran) (PTHF), Carbowax 20M (CW20M), short chain poly(dimethyl siloxane) (SC PDMS) and polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer (PEG-PPG-PEG). CW20M coated FPSE media was found to be the most efficient extraction media for the analytes of interest in the intended study. The developed methodology was applied to the analysis of orange juice obtained from fresh oranges and oranges after storing at 5°C for two months in order to identify the best chemical markers, both volatiles and non-volatiles, attributed to the freshness of orange. For this purpose, aliquots of the same juice extracts were analysed by GC–MS as well as by UPLC–QTOF–MS. Monoterpenes and terpenoids, such as terpinene, citronellal or estragole were among the volatile compounds that endured the biggest decrease after the extended storage period. Three non-volatile compounds including one amide (subaphyllin) and two flavanoids (tangeretin and nobiletin) also showed a clear decrease in signal intensity (>70%) after orange stored for two months.

Analysis of chemical constituents in an herbal formula Jitong Ning Tablet

Jitong Ning Tablet (JTNT), a traditional Chinese herbal formula, consists of Eucommia ulmodies oliv, Angelicae pubescentis radix, Aconiti radix cocta, Corydalis yanhusuo w.t. wang, Glycyrrhizae radix et rhizoma, Paeoniae radix rubra and Radix puerariae. It has been demonstrated to show protective effects on ankylosing spondylitis and anti-inflammatory effects. The chemical compositions of JTNT, playing a key role in quality control, remain unknown. In this study, an ultra-performance liquid chromatography combined with quadrupole time of flight mass spectrometry (UPLC-Q–TOF–MS) method in both positive and negative ion mode was established to investigate the chemical constituents of JTNT formula. In total, 162 compounds including flavonoids, triterpenoids, coumarins, alkaloids, phenylpropionic acids, lignans, terpenoids, and organic acids were detected, 152 of which were unambiguously or tentatively identified by comparing their retention times and accurate mass measurement with reference compounds and data in literatures. Our results would benefit quality control and chemical basis for JTNT.

Comparison of secondary metabolite changes in Camellia sinensis leaves depending on the growth stage

To improve tea leaves' utility as a functional crop, it is necessary to understand the distribution and alteration of bioactive secondary metabolites during different growth stages. In the present study, secondary metabolites changes in C. sinensis leaves were investigated according to growth stage using ultra-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC–QTof MS) with multivariate analysis. Through principal component analysis of the metabolites, patterns could be distinguished from samples harvested between April and August. On the loading plot, significant changes in the contents of metabolites were found during growth, and two gallotannins (4 and 10), three flavan-3-ols (6, 7, and 17), two flavonols (14 and 16), and two theaflavins (29 and 31) were evaluated as growth markers among thirty-one isolated metabolites. In particular, the flavonols and theaflavins increased gradually, whereas gallotannins and flavan-3-ols decreased continuously depending on the growth stage. A possible pathway could be deduced using metabolomics analysis, and information regarding physiological characterization and optimal harvesting time was obtained.

Detection and Identification of Leachables in Vaccine from Plastic Packaging Materials Using UPLC-QTOF MS with Self-Built Polymer Additives Library.

The direct contact of plastic parts with the medical products raises the possibility that plastic-related contaminants (leachables) may be present in the finished medical product. The leachable components from plastic materials may impact the safety and efficacy of the final medical product, so identification and determination of the leachables are essential for the safety assessment of medical products. A method to identify main leachables-polymer additives in medical products was developed by ultraperformance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-QTOF MS) and a self-built library. The library contains 174 additives and the information on their names, formulas, structures, retention times, fragments, classifications, origin, and corresponding MS(E) and MSMS spectra. The reliability of the construction process of the library was guaranteed by the system stability and suitability test. Identification parameters of library application, such as mass error, retention times, fragments, and isotope pattern, were evaluated. Leachables in real vaccine and the intermediates were identified using automatic library searching. In vaccine, the peak m/z 239.0887 that could not be assigned by the library was identified as dimethyl 2-hydroxy-1,3-cyclohexanedicarboxylate using a series of elucidation tools. As a result, the concentrations of leachables in vaccine and the intermediates ranged from 0.85 to 21.91 μg/L.

Determination of benzoxazinoids in wheat and rye beers by HPLC-DAD and UPLC-QTOF MS

Phenolic compounds in beer have received considerable interest. Besides the more typical phenolic acids and flavonoids, beer contains also lesser-known compounds, such as hordatines, their agmatine precursors and other phenolamines. Current work shows that beers brewed from wheat or rye malts, in addition to barley malts, contain benzoxazinoids, a group of nitrogen containing secondary metabolites typical to wheat and rye. In this work, HPLC-DAD was used for the quantification of major benzoxazinoids in 32 wheat and four rye beers. Of the wheat beers 22 samples and all of the rye beers contained benzoxazinoids, or their breakdown products. Concentrations of DIBOA (2,4-dihydroxy-1,4-benzoxazin-3-one) (as aglycon) varied from 1.7 to 21.9mg/l in wheat beers and from 5.6 to 31.6mg/l in rye beers. Breakdown products BOA (benzoxazolin-2-one), found in 15 beers, and MBOA (6-methoxy-benzoxazolin-2-one), found in two beers, were measured at concentrations ranging from 2.4 to 10.7mg/l and 8.4 to 10.5mg/l, respectively.Identification of benzoxazinoids by UPLC-QTOF MS was done on selected beers. Benzoxazinoid profiles varied greatly between different wheat beers, and compared to rye beers the chemical diversity of benzoxazinoids was higher. As far as the authors know, this is the first time that other benzoxazinoids, rather than just the decomposition products BOA or MBOA, have been reported in beer. The results also show that benzoxazinoids can be present in beer glycosylated with three or four hexose units.

Characterization of polyphenols in Agastache rugosa leaves and inflorescences by UPLC–qTOF–MS following FCPC separation

ABSTRACTThe accurate profiling of Agastache rugosa phenolic compounds is an indispensable step toward better understanding of the medicinal properties of the species. The applied method based on coupling fast centrifugal partition chromatography and UPLC–qTOF–MS is an alternative and rapid method for the separation and preliminary purification of compounds included in crude extract and can facilitate the detection of minor compounds. Samples were prepared by the extraction of leaves and inflorescences with methanol, dichloromethane, and ethyl acetate. Polyphenolic compounds were separated using fast centrifugal partition chromatography (FCPC) and analyzed by UPLC–qTOF–MS. Rosmarinic acid, chlorogenic acid, and tilianin content were determined in aerial parts during the growth season and in plants of different age. The developed analytical method used in our experiments improved the identification of phenolic compounds and led to the detection of compounds that had not been found in A. rugosa previously.

UPLC–QTOF–MS and NMR analyses of graviola (Annona muricata) leaves

Graviola leaves (Annona muricata L., Annonaceae) are used by some people to try to treat or even cure cancer, even though over-consumption of the fruit, which contains the neurotoxins annonacin and squamocin has caused an atypical form of Parkinson's disease. In previous analyses, the fruits were extracted with methanol under ambient conditions before analyses. In the present study, UPLC–QTOF–MS and NMR were used to analyze freeze-dried graviola leaves that were extracted using dry methanol and ethanol at 100°C and 10MPa (100atm) pressure in a sealed container. Methanol solubilized 33% of the metabolites in the lyophilized leaves. Ethanol solubilized 41% of metabolites in the lyophilized leaves. The concentrations of total phenolic compounds were 100.3±2.8 and 93.2±2.0mg gallic acid equivalents per g of sample, for the methanolic and ethanolic extracts, respectively. Moreover, the toxicophore (unsaturated γ-lactone) that is present in neurotoxic acetogenins was found in the lipophilic portion of this extract. The concentrations of the neurotoxins annonacin and squamocin were found by UPLC–QTOF–MS to be 305.6±28.3 and 17.4±0.89μg/g-dw, respectively, in the dried leaves. Pressurized methanol solubilized more annonacin and squamocin than ethanol. On the other hand, a hot, aqueous infusion solubilized only 0.213% of the annonacin and too little of the squamocin to be detected. So, graviola leaves contain significant amounts of the neurotoxins annonacin and squamocin, as well as some potentially healthy phenolic compounds. Finally, the potential neurotoxicity of whole leaves in dietary supplements could be much higher than that of a tea (hot aqueous infusion) that is made from them.

An investigative study on differentiation of citrus fruit/fruit juices by UPLC-QToF MS and chemometrics

In the study presented, the potential of coupling chemometrics and mass spectrometry (UPLC-QToF MS) data for distinguishing the origin and variety of citrus fruit/fruit juices was investigated. Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and soft independent modelling by class analogy (SIMCA) were employed. Clustering of citrus fruits (orange, grapefruit, mandarin, and pomelo) and oranges of various geographical/botanical origin was revealed using PCA on data produced in both negative (goodness of fit, R2(cum) = 0.67–0.92, and predictability, Q2(cum) = 0.56–0.88) and positive (R2(cum) = 0.58–0.85 and Q2(cum) = 0.47–0.80) ionisation mode. PLS-DA and SIMCA confirmed the results (with 100% recognition ability obtained for citrus fruits/orange models and fresh squeezed commercial orange juice, while classification success of 80% was achieved for commercial orange juice prepared from concentrate) and showed that the category models for the class can be sensitive and highly specific. Characteristic compounds responsible for the discrimination were identified. The applicability of the models was tested with an external data set of fruit juices adulterated with other fruit juices down to 1% and diluted with water down to 5%. Using Coomans' plots, adulterated samples were easily distinguished from authentic samples showing the possibility of applying this method as a rapid screening technique to trace or confirm the origin of citrus fruit/fruit juices and detect fraud.

An investigative study on discrimination of honey of various floral and geographical origins using UPLC-QToF MS and multivariate data analysis

An untargeted metabolomics approach was applied for the discrimination of honey of various floral and geographical origins using ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-QToF MS). Evaluation of data by multivariate data analysis allowed the discrimination of New Zealand and Australian honeys from honeys originating in other countries. It was also possible to differentiate between mono- and polyfloral honeys within one region, as well as between some monofloral honeys of various geographical origins. Characteristic markers, contributing to the segregation of different honey types, were selected and characterized.

Discrimination of honey of different floral origins by a combination of various chemical parameters

Honey is a high value food commodity with recognized nutraceutical properties. A primary driver of the value of honey is its floral origin. The feasibility of applying multivariate data analysis to various chemical parameters for the discrimination of honeys was explored. This approach was applied to four authentic honeys with different floral origins (rata, kamahi, clover and manuka) obtained from producers in New Zealand. Results from elemental profiling, stable isotope analysis, metabolomics (UPLC-QToF MS), and NIR, FT-IR, and Raman spectroscopic fingerprinting were analyzed. Orthogonal partial least square discriminant analysis (OPLS-DA) was used to determine which technique or combination of techniques provided the best classification and prediction abilities. Good prediction values were achieved using metabolite data (for all four honeys, Q2=0.52; for manuka and clover, Q2=0.76) and the trace element/isotopic data (for manuka and clover, Q2=0.65), while the other chemical parameters showed promise when combined (for manuka and clover, Q2=0.43).

UPLC-QTOF (ESI +) MS Analysis Applied for Targeted Profiling of Human Urine Amino Acids

Amino acids, the building blocks of proteins are providing fundamental information about metabolic status and early disease diagnosis. For an accurate interpretation of metabolic status, amino acid reference values for healthy humans are required. Most studies have pointed out that, the most accurate, reliable and sensitive tool to evaluate amino acids in biofluids ( blood or urine) is liquid chromatography coupled with mass spetrometry (LC/MS). The aim of this study was to determine and optimize the urine amino acids profile by LC-QTOF (ESI+) MS, comparatively, using two generic samples from a healthy male and female. Urine aminoacids were purified using solid phase extraction, a pre-column derivatization and liquid/liquid extraction according to Ez-Faast kit (Phenomenex). The derivatized samples were analyzed by LC-QTOF-(ESI+)-MS and data were processed by Data Analysis-Extracted Ion Chromatogram software. A number of 16 amino acids were found in both samples, the male urine showed higher values for 10 amino acids (hydroxyproline, alanine, sarcosine, lysine, histidine, tryptophan, leucine, phenylalanine, cysteine and tyrosine), while glutamine and valine were higher in female urine. Most of the amino acids identified were essential amino acids found in both cases like: glutamine, proline, lysine, histidine, valine, tryptophan, leucine and phenylalanine. The main differences between the male vs female aminoacid fingerprints of urine were mainly quantitative and not qualitative. The amino acid concentrations ranged from 1.48 nmol/mg creatinine (proline) to 203.13 nmol/mg (histidine). The concentration of amino acids in man were 2 times higher than for female, while the percentages of essential amino acids were similar in both gender.

Evaluation and validation of an accurate mass screening method for the analysis of pesticides in fruits and vegetables using liquid chromatography–quadrupole-time of flight–mass spectrometry with automated detection

This study reports the development and validation of a screening method for the detection of pesticides in 11 different fruit and vegetable commodities. The method was based on ultra performance liquid chromatography–quadrupole-time of flight–mass spectrometry (UPLC–QTOF–MS). The objective was to validate the method in accordance with the SANCO guidance document (12571/2013) on analytical quality control and validation procedures for pesticide residues analysis in food and feed. Samples were spiked with 199 pesticides, each at two different concentrations (0.01 and 0.05mgkg−1) and extracted using the QuEChERS approach. Extracts were analysed by UPLC–QTOF–MS using generic acquisition parameters. Automated detection and data filtering were performed using the UNIFI™ software and the peaks detected evaluated against a proprietary scientific library containing information for 504 pesticides. The results obtained using different data processing parameters were evaluated for 4378 pesticide/commodities combinations at 0.01 and 0.05mgkg−1. Using mass accuracy (±5ppm) with retention time (±0.2min) and a low response threshold (100 counts) the validated Screening Detection Limits (SDLs) were 0.01mgkg−1 and 0.05mgkg−1 for 57% and 79% of the compounds tested, respectively, with an average of 10 false detects per sample analysis. Excluding the most complex matrices (onion and leek) the detection rates increased to 69% and 87%, respectively. The use of additional parameters such as isotopic pattern and fragmentation information further reduced the number of false detects but compromised the detection rates, particularly at lower residue concentrations. The challenges associated with the validation and subsequent implementation of a pesticide multi-residue screening method are also discussed.

The Study of Senkyunolide I Degradation Products by Ultra-High Performance Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry

Ligusticum chuanxiongHort. (Umbelliferae) has been prescribed widely to treat cardiovascular diseases in China for centuries. Senkyunolide I is a major bioactive component inL. chuanxiongthat shows pharmacological activity against migraines and oxidative damage. Here, we identified the degradation products of senkyunolide I under different conditions (temperature, light alkaline) by ultra-high-performance liquid chromatography–quadrupole time-of-flight–tandem mass spectrometry (UPLC-QTOF-MS) analyses. Senkyunolide I was separated on an ACQUITY UPLC HSS T3 C18 (100 mm × 2.1 mm i.d., 1.8 μm) column using a binary eluent under gradient conditions. Analytes were detected by ESI/QTOF–MS/MS in positive ion mode to obtain MS and MS/MS spectra together with extracted molecular weights. Upon comparison with reference data, we concluded that senkyunolide I undergoes a ring-opening reaction under alkaline conditions (pH &gt;10.0), and dual-key addition or hydration on 3,4-unsaturated bonds and branched terminal hydroxyl groups under high-temperature and aerobic conditions. With auxiliary application1H-NMR, we determined that partial isomerization of senkyunolide I takes place under bright light. In the method detailed here, the advantages of separation and identification of a complex system of small and medium-sized molecules was exploited using UPLC–QTOF–MS, not only to avoid complicated separation and purification, but also to isolate and identify trace amounts of degradation products that were previously difficult to identify.