Triple Quadrupole Mass Spectrometer System Research Articles

Optimization of cultivation system for Bacillus Siamese strain and its biocontrol effect on postharvest Colletotrichum gloeosporioides

In this study, we established an effective cultivation system for Bacillus Siamese (N-1), identified key antibacterial substances, and explored the underlying mechanisms of optimized N-1 fermentation for controlling pathogens. Our results demonstrate that the optimized system significantly enhanced the inhibitory effect of N-1 on five types of pathogens affecting tropical fruits. Additionally, non-targeted metabolomics analysis and ultra-high performance liquid chromatography triple quadrupole mass spectrometer system (UPLC-MS/MS) revealed the presence of lipopeptides, including Surfactin and FengycinA, in the optimized fermentation. Furthermore, in vitro experiments indicated that lipopeptide treatment (LT) at a concentration of 3.125 mg mL−1 significantly distorted the hyphae, decreased the activity of antioxidant enzymes, increased the levels of reactive oxygen species (ROS), malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents, and enhanced protein exosmosis rate of C. gloeosporioides. Moreover, LT markedly reduced the activities of energy metabolism-related enzymes, including succinate dehydrogenase (SDH), Na+K+-ATPase, and Ca2+Mg2+-ATPase, as well as ATP content, leading to apoptosis of C. gloeosporioides. In vivo experiments revealed that LT significantly inhibited the expansion of disease spots caused by C. gloeosporioides in mango fruit. These findings suggest that the established culture system could serve as a potential strategy to enhance biocontrol efficacy and prevent fruit decay.

Integration of targeted metabolome and transcript profiling of Pseudomonas syringae-triggered changes in defence-related phytochemicals in oat plants

Main conclusionA gene-to-metabolite approach afforded new insights regarding defence mechanisms in oat plants that can be incorporated into plant breeding programmes for the selection of markers and genes related to disease resistance.Monitoring metabolite levels and changes therein can complement and corroborate transcriptome (mRNA) data on plant–pathogen interactions, thus revealing mechanisms involved in pathogen attack and host defence. A multi-omics approach thus adds new layers of information such as identifying metabolites with antimicrobial properties, elucidating metabolomic profiles of infected and non-infected plants, and reveals pathogenic requirements for infection and colonisation. In this study, two oat cultivars (Dunnart and SWK001) were inoculated with Pseudomonas syringae pathovars, pathogenic and non-pathogenic on oat. Following inoculation, metabolites were extracted with methanol from leaf tissues at 2, 4 and 6 days post-infection and analysed by multiple reaction monitoring (MRM) on a triple quadrupole mass spectrometer system. Relatedly, mRNA was isolated at the same time points, and the cDNA analysed by quantitative PCR (RT-qPCR) for expression levels of selected gene transcripts associated with avenanthramide (Avn) biosynthesis. The targeted amino acids, hydroxycinnamic acids and Avns were successfully quantified. Distinct cultivar-specific differences in the metabolite responses were observed in response to pathogenic and non-pathogenic strains. Trends in aromatic amino acids and hydroxycinnamic acids seem to indicate stronger activation and flux through these pathways in Dunnart as compared to SWK001. A positive correlation between hydroxycinnamoyl-CoA:hydroxyanthranilate N-hydroxycinnamoyl transferase (HHT) gene expression and the abundance of Avn A in both cultivars was documented. However, transcript profiling of selected genes involved in Avn synthesis did not reveal a clear pattern to distinguish between the tolerant and susceptible cultivars.Graphical abstract

A robust LC-MS/MS method to measure 8-oxoGuo, 8-oxodG, and NMN in human serum and urine

ObjectiveTo establish and validate a robust LC-MS/MS method for simultaneously measuring 8-oxoGuo, 8-oxodG, and NMN in serum and urine to evaluate the oxidative stress status. MethodsA Waters TQ-XS triple quadrupole mass spectrometer system coupled with an Acquity UPLC Primer HSS T3 column was chosen. The clinical performance was verified according to the CLSI C62-A and EP-15 guidelines. Furthermore, matched serum and urine samples from 22 apparently healthy check-ups, 20 patients with atherosclerosis, and 18 individuals with dementia were evaluated. ResultsThe recovery for serum 8-oxoGuo, urine 8-oxoGuo, serum 8-oxodG, urine 8-oxodG, serum NMN, and urine NMN was 88.8–112.4%, 102.4–114.1%, 88.5–107.7%, 94.9–102.6%, 98.4–108.9%, and 88.5–108.6%, respectively. Based on the inter-assay results, total coefficient of variation, matrix effect, and carryover, the LC-MS/MS method was deemed robust. The limit of quantification was 0.017, 0.018, and 0.150 nmol/L for 8-oxoGuo, 8-oxodG, and NMN, respectively, which are suitable for accurate measurements in human serum and urine samples. Higher 8-oxoGuo and 8-oxodG levels and lower NMN levels, indicative of significantly higher oxidative stress status, were found in patients with dementia compared to healthy subjects. ConclusionWe established and validated a robust LC-MS/MS method to simultaneously measure 8-oxoGuo, 8-oxodG, and NMN in serum and urine.

A Dilute-and-Shoot LC-MS/MS Method for Screening of 43 Cardiovascular Drugs in Human Urine

A simple, specific, and economical LC-MS/MS method was investigated for the screening of 43 prescribed antihypertensive and related drugs in human urine. The urine samples were simply prepared by diluting and mixing with internal standard before directly introduced to the LC-MS/MS system, which is fast, straightforward, and cost-effective. Fractional factorial, Box-Behnken, and I-optimal design were applied to screen and optimize the mass spectrometric and chromatographic factors. The analysis was carried out on a triple quadrupole mass spectrometer system utilizing multiple reaction monitoring with positive and negative electrospray ionization method. Chromatographic separation was performed on a Thermo Scientific Accucore RP-MS column (50 × 3.0 mm ID., 2.6 μm) using two separate gradient elution programs established with the same mobile phases. Chromatographic separation was performed within 12 min. The optimal method was validated based on FDA guideline. The results indicated that the assay was specific, reproducible, and sensitive with the limit of detection from 0.1 to 50.0 μg/L. The method was linear for all analytes with coefficient of determination ranging from 0.9870 to 0.9981. The intra-assay precision was from 1.44 to 19.87% and the inter-assay precision was between 2.69 and 18.54% with the recovery rate ranges from 84.54 to 119.78% for all drugs measured. All analytes in urine samples were stable for 24 h at 25℃, and for 2 weeks at -60℃. The developed method improves on currently existing methods by including larger number of cardiovascular medications and better sensitivity of 12 analytes.

Development, validation and evaluation of a quantitative method for the analysis of twenty-four new psychoactive substances in oral fluid by LC–MS/MS

The use of new psychoactive substances (NPS) has been recognized worldwide at an alarming rate. Oral fluid collection is becoming more prevalent as a matrix for evaluating drug consumption. In this study, a specific, quick and non-invasive method for detection and quantitation of twenty-four synthetic cannabinoids and cathinone derivatives, including ten not previously reported NPS in oral fluid was performed. A quantitative method was developed on a liquid chromatography coupled to a triple quadrupole mass spectrometer system operated in dynamic multiple reaction monitoring (dMRM) mode using solid phase extraction (SPE) as pre-concentration step. Analytical separation of the target drugs was reached in a total elution time of 10 min. The developed method was validated according to the ASB standard 036. Overall bias and precision of the method were within ±20% for twenty-three compounds. All drugs showed acceptable linearity with R2 values greater than 0.98, and LLOQ values of 0.25 ng/mL and 1.0 ng/mL for selected NPS. The overall bias for a performed blind verification study was 7%. Our results demonstrate the method is suitable for quantifying NPS in oral fluid through solid phase extraction and analysis using LC–MS/MS.

Quantification of metronidazole in human plasma using a highly sensitive and rugged LC-MS/MS method for a bioequivalence study.

A highly sensitive, selective and rugged method has been described for the quantification of metronidazole (MTZ) in human plasma by liquid chromatography-tandem mass spectrometry using metronidazole-d4 as the internal standard (IS). The analyte and the IS were extracted from 100 μL plasma by liquid-liquid extraction. The clear samples obtained were chromatographed on an ACE C18 (100 × 4.6 mm, 5 μm) column using acetonitrile and 10.0 mm ammonium formate in water, pH 4.00 (80:20, v/v) as the mobile phase. A triple quadrupole mass spectrometer system equipped with turbo ion spray source and operated in multiple reaction monitoring mode was used for the detection and quantification of MTZ. The calibration range was established from 0.01 to 10.0 μg/mL. The results of validation testing for precision and accuracy, selectivity, matrix effects, recovery and stability complied with current bioanalytical guidelines. A run time of 3.0 min permitted analysis of more than 300 samples in a day. The method was applied to a bioequivalence study with 250 mg MTZ tablet formulation in 24 healthy Indian males.

A nontargeted screening method for covalent DNA adducts and DNA modification selectivity using liquid chromatography-tandem mass spectrometry

A method for nontargeted screening for covalent DNA adducts was developed using combination of neutral loss scan and product ion scan in a hybrid linear-ion-trap - triple quadrupole mass spectrometer system. DNA 2′-deoxynucleosides and adducts eluted from liquid chromatography were first analyzed in neutral loss mode to screen for the neutral loss of the deoxyribose moiety ([M+H-116]+) from the protonated molecular ion ([M+H]+). The product ion scan was subsequently used to elucidate the structures for the molecular ions observed from the peaks in the neutral loss scan chromatogram. The synthesized DNA adducts were used to evaluate the developed method by reaction of 20-mer DNA oligonucleotide with two direct agents respectively, specifically phenyl glycidyl ether and styrene-7,8-oxide. The modification selectivity of two compounds to the four nitrogenous bases on DNA sequence was also investigated in this study. The results showed that the two compounds had different modification selectivity to the four bases. Both compounds could modify all four nitrogenous bases (i.e. adenine, guanine, thymine, and cytosine) on DNA sequences to form various covalent DNA adducts. While phenyl glycidyl ether modified almost all of thymidine on DNA sequence, styrene-7,8-oxide, on the other hand, modified only a small portion of thymidine. The developed method proved possibly a potential tool for screening of unknown DNA adducts as exposure biomarkers of contaminants to human in the environment.

Pseudo-MS3Approach Using Electrospray Mass Spectrometry (ESI-MS/MS) to Characterize Certain (2E)-2-[3-(1H-Imidazol-1-yl)-1-phenylpropylidene]hydrazinecarboxamide Derivatives

An approach for the use of in-source fragmentation with electrospray ionization followed by product ion scan in a triple quadrupole mass spectrometer system is described. This approach is based on the elucidation of the various fragmentation pathways by further dissociation of each fragment ion in the ion spectrum. This can be achieved predominately, by combining fragmentor voltage induced dissociation (in-source fragmentation) with subsequent collision-induced dissociation; this process can be referred to as pseudo-MS3scan mode. This technique permitted unambiguous assignment and provided sufficient sensitivity and specificity. It is advantageous for structure elucidation of unknown compounds. We investigate the possibility of using in-source fragmentation with the diverse novel chemical entities encompassing different substituents. This process was intended to improve the qualitative capability of tandem mass spectrometry simulating the MS3of ion trap for studying fragmentation mechanisms. The approach is to implement the investigated technique as a well established tool for the characterization of new pharmacologically important chemical entities. The data presented in this paper provided useful information on the effect of different substituents on the ionization/fragmentation processes and can be used in the characterization of (2E)-2-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]-hydrazinecarboxamide derivatives3a–h.

Multistage Fragmentation of Ion Trap Mass Spectrometry System and Pseudo-MS3of Triple Quadrupole Mass Spectrometry Characterize Certain (E)-3-(Dimethylamino)-1-arylprop-2-en-1-ones: A Comparative Study

A new approach was recently introduced to improve the structure elucidation power of tandem mass spectrometry simulating the MS3 of ion trap mass spectrometry system overcoming the different drawbacks of the latter. The fact that collision induced dissociation in the triple quadrupole mass spectrometer system provides richer fragment ions compared to those achieved in the ion trap mass spectrometer system utilizing resonance excitation. Moreover, extracting comprehensive spectra in the ion trap needs multistage fragmentation, whereas similar fragment ions may be acquired from one stage product ion scan using the triple quadrupole mass spectrometer. The new strategy was proven to enhance the qualitative performance of tandem mass spectrometry for structural elucidation of different chemical entities. In the current study we are endeavoring to prove our hypothesis of the efficiency of the new pseudo-MS3 technique via its comparison with the MS3 mode of ion trap mass spectrometry system. Ten pharmacologically and synthetically important (E)-3-(dimethylamino)-1-arylprop-2-en-1-ones (enaminones 4a–j) were chosen as model compounds for this study. This strategy permitted rigorous identification of all fragment ions using triple quadrupole mass spectrometer with sufficient specificity. It can be used to elucidate structures of different unknown components. The data presented in this paper provide clear evidence that our new pseudo-MS3 may simulate the MS3 of ion trap spectrometry system.

Induced in-source fragmentation pattern of certain novel (1Z,2E)-N-(aryl)propanehydrazonoyl chlorides by electrospray mass spectrometry (ESI-MS/MS)

BackgroundCollision induced dissociation (CID) in the triple quadrupole mass spectrometer system (QQQ) typically yields more abundant fragment ions than those produced with resonance excitation in the presence of helium gas in the ion trap mass spectrometer system (IT). Detailed product ion spectra can be obtained from one stage MS2 scan using the QQQ. In contrast, generating the same number of fragment ions in the ion trap requires multiple stages of fragmentation (MSn) using CID via in-trap resonance excitation with the associated time penalties and drop in sensitivity.ResultsThe use of in-source fragmentation with electrospray ionization (ESI) followed by product ion scan (MS2) in a triple quadrupole mass spectrometer system, was demonstrated. This process enhances the qualitative power of tandem mass spectrometry to simulate the MS3 of ion trap for a comprehensive study of fragmentation mechanisms. A five pharmacologically significant (1Z, 2E)-N-arylpropanehydrazonoyl chlorides (3a-e) were chosen as model compounds for this study. In this work, detailed fragmentation pathways were elucidated by further dissociation of each fragment ion in the ion spectrum, essentially, by incorporating fragmentor voltage induced dissociation (in-source fragmentation) and isolation of fragments in a quadrupole cell Q1. Subsequently, CID occurs in cell, Q2, and fragment ions are analyzed in Q3 operated in product ion mode this process can be referred to as pseudo-MS3 scan mode.ConclusionsThis approach allowed unambiguous assignment of all fragment ions using tandem mass spectrometer and provided adequate sensitivity and selectivity. It is beneficial for structure determination of unknown trace components. The data presented in this paper provide useful information on the effect of different substituents on the ionization/fragmentation processes and can be used in the characterization of this important class of compounds.

High Throughput Quantitative Bioanalytical LC/MS/MS Determination of Gemifloxacin in Human Urine

A highly specific, sensitive, and rapid method, to quantify gemifloxacin in human urine using HPLC coupled to the triple quadrupole mass spectrometer system, was developed and validated. Gemifloxacin and ofloxacin (internal standard) were rapidly extracted from urine samples without any tedious pretreatment procedure. Urine samples were filtered through a Millex‐GP, 0.22 μm syringe filter. Optimal chromatographic separation of the analytes was achieved on Zorbax SB‐C18 (30 mm × 2 mm i.d., 3.5 μm maintained at ambient temperature). The mobile phase consisted of 0.1% formic acid (pH 3.2) and acetonitrile (80 : 20) and a flow rate of 0.2 mL min−1 for 4 min. The analytes were monitored by electrospray ionization in positive ion multiple reaction monitoring mode. The method provided a linear response (r = 0.9998) from a quantitation range of 5 ng mL−1 to at least 500 ng mL−1. The mean extraction recovery % of gemifloxacin from spiked human urine was 101.33 ± 2.58%. The reproducibility of the method was reliable with the intra‐ and inter‐day precision of <2% and accuracy within 2%. The established method was reliably applied for the determination of gemifloxacin in volunteers’ urine samples with the mean recoveries of gemifloxacin from Factive tablets 320 mg > 97.0%.

A triple quadrupole mass spectrometer system for studies of gas-phase combustion chemistry of energetic materials

A triple quadrupole mass spectrometer (TQMS) system utilizing the collision-induced dissociation process has been constructed for studies of gas-phase combustion chemistry of energetic materials under various conditions of pressure and incident laser heat flux. A unique feature of the TQMS system is its capability to differentiate species at the same mass-to-charge value and to identify chemical structures of the gaseous species evolved from the energetic materials, through the recognition of the fragmentation characteristics of chemical functional groups in species. Two different settings for high and low collision energy modes were developed for the daughter mode of operation. A calibration method at the two settings in the daughter mode was also developed for the quantification of the measured species. The TQMS system developed also includes integrated vacuum system, quartz microprobes for gas species sampling, customized software for data acquisition and data reduction. Typical results are presented to illustrate the methods used to differentiate the measured species and to identify their chemical structures.

Collision cross sections of myoglobin and cytochrome c ions with Ne, Ar, and Kr

The energy losses of ions of myoglobin and cytochrome c in collisions with Ne, Ar, and Kr have been measured with a triple quadrupole mass spectrometer system. The results have been interpreted with drag coefficients, suitable for the case of an object moving through a low density gas, to give collision cross sections or, equivalently, projection areas. For a given charge state, these cross sections with Ne, Ar, and Kr are nearly identical. No evidence is found for substantial contributions to the cross section from ion-induced dipole forces. Comparisons of cross sections obtained with different gases and comparisons to literature cross sections measured by ion mobility suggest that a “diffuse” scattering model, suitable for collisions with a rough surface, gives the best description of collisions between protein ions and neutrals.

Collision-Induced Dissociation of Vanadium−Carbon Cluster Cations

Collision-induced dissociation (CID) studies of vanadium−carbon clusters were made employing a triple quadrupole mass spectrometer system coupled with a laser vaporization source. The results reveal that the primary dissociation channel is loss of a metal atom for all but V8C14+, which loses C3, and V9C14+, which loses both V and VC2. These findings are in general agreement with earlier ones reported for the titanium system, except that under single-collision conditions V8C14+ loses a C3 unit to become V8C11+, while Ti8C14+ loses Ti. Importantly, we show that both the met-car V8C12+ and V8C13+ are significantly more resistant to dissociation than the neighboring V8C11+ cluster species. In addition to reporting the primary fragmentation products of several VxCy+ clusters, we also present the results of studies of the multiple-collision dissociation patterns of both V8C12+ and V8C13+, which are observed to undergo C2 and C3 loss after some metal loss has occurred. These findings are consistent with the building patterns observed for these clusters and our proposed structure for V8C12+. Through study of the dissociation of V9C12+, the ionization energy of V8C12 is found to be less than that of the vanadium atom, i.e., less than 6.74 eV, in accord with theoretical predictions.

Improved Collisionally Activated Dissociation Efficiency and Mass Resolution on a Triple Quadrupole Mass Spectrometer System

Collsionally activated dissociation efficiency and fragment ion mass resolution have been characterized on a triple quadrupole mass spectrometer equipped with an enclosed collision cell which is operated at relatively high pressure. The higher pressure results in improved efficiency (and therefore improved ion transmission) and better mass resolution than has been obtained previously with collision cells operated at lower pressure. Efficiencies of 30-50%, measured as the fractions of original precursor ion in Q1 which are detected as resolved fragment ions, are typical for singly charged ions, compared with 5-10% achieved previously. Mass resolution of fragment ions is improved to the point that the isotopes from quadruply charged fragment ions can be resolved

Ion—Molecule reactions of environmentally significant organotin compounds in a triple quadrupole mass spectrometer system

AbstractTandem MS techniques have been used to examine the formation of cluster ions derived from organotin compounds of environmental significance. The cluster formation was based on the addition of either water or methanol molecules (common HPLC solvents) to a cationic species derived from the organotin compound. For the compounds and conditions studied, cluster adducts were only observed from trisubstituted tin cations. The results show that, in high‐pressure ionization methods used in the interface between HPLC and MS, the tin atom may be associated with a range of ions depending on the system parameters, and that care should be taken if selection ion monitoring (SIM) is to be used.

Metabolism studies of the antischistosomal drug praziquantel using tandem mass spectrometry: Distribution of parent drug and ten metabolites obtained from control and schistosome-infected mouse urine

The collisionally activated dissociation spectrum of the antischistosomal drug praziquantel (PZQ) has many structure-specific fragmentations which permit identification of PZQ and seventeen of its hydroxylated metabolites in mouse urine. These fragmentations may also be used to quantify the metabolic pattern of PZQ. In the present study, a triple-quadrupole mass spectrometer system has been used to generate [M + H]+ ions for PZQ and its monohydroxy, dihydroxy and trihydroxy metabolites which yield daughter ions capable of quantifying PZQ and ten of these metabolites. The goal of these experiments was to evaluate the effect of this hepatic infection on drug metabolism. This was accomplished in two steps. First, the amount of unmetabolized, mono- and dihydroxylated PZQ was established from the [M + H]+ ions. Then the specific metabolites at each level of hydroxylation were determined from daughter ion spectra. The product of these two values produces the metabolite pattern. The reproducibility of these assays ranged from good, with a coefficient of variation of 3% for the most abundant metabolite, to poor (43%) for PZQ, which is only 1% of the total elimination pattern. The excretion of unchanged PZQ and two dihydroxylated metabolites was enhanced in animals bearing schistosomiasis compared to control mice, while a third dihydroxylated metabolite was depressed.

Time-resolved analytical pyrolysis studies of nitramine decomposition with a triple quadrupole mass spectrometer system

An energetic nitramine, cyclotrimethylenetrinitramine (RDX), has been studied over selected thermal ranges and environments with a pyrolysis unit interfaced to an atmospheric pressure chemical ionization tandem mass spectrometer (MS-MS) system. Programmed and pulsed thermolytic degradation conditions under oxidative and non-oxidative atmospheres resulted in complex product distributions. Use of selected boron-containing compounds gave evidence of catalytic activity in the RDX degradation. Identification by daughter-ion MS-MS analysis was attempted for key volatiles of m/z 46, 60, 74, 75, 85, 97, 98, and 103. An integrated thermal degradation profile of RDX was thus probed by monitoring the volatile products as they were generated during slow programmed heating (60°C/min) from ambient to temperatures near the RDX melting/decomposition region (190–220°C). Implications of enhanced nitramine performance are suggested.

Development of a totally computer-controlled triple quadrupole mass spectrometer system

A totally computer-controlled triple quadrupole mass spectrometer (TQMS) is described. It has a number of unique features not available on current commercial instruments, including: complete computer control of source and all ion axial potentials; use of dual computers for data acquisition and data processing; and capability for self-adaptive control of experiments. Furthermore, it has been possible to produce this instrument at a cost significantly below that of commercial instruments. This triple quadrupole mass spectrometer has been constructed using components commercially available from several different manufacturers. The source is a standard Hewlett-Packard 5985B GC/MS source. The two quadrupole analyzers and the quadrupole CAD region contain Balzers QMA 150 rods with Balzers QMG 511 rf controllers for the analyzers and a Balzers QHS-511 controller for the CAD region. The pulsed-positive-ion-negative-ion-chemical ionization (PPINICI) detector is made by Finnigan Corporation. The mechanical and electronics design were developed at LLNL for linking these diverse elements into a functional TQMS as described. The computer design for total control of the system is unique in that two separate LSI-11/23 minicomputers and assorted I/O peripherals and interfaces from several manufacturers are used. The evolution of this design concept from totally computer-controlled instrumentation into future self-adaptive or ‘‘expert’’ systems for instrumental analysis is described. Operational characteristics of the instrument and initial results from experiments involving the analysis of the high explosive HMX (1,3,5,7-Tetranitro-1,3,5,7-Tetrazacyclooctane) are presented.