Linear Ion Trap Mass Spectrometry Research Articles

Pseudotargeted metabolomics method and its application in erastin-stimulated gastric adenocarcinoma cells based on liquid chromatography with tandem mass spectrometry

Erastin, a classical ferroptosis inducer, exerts cytotoxicity in several types of cancer cells including gastric cancer cells. However, the mechanism of erastin in regulating metabolic pathways in gastric cancer remains largely unclear. To investigate the gastric cellular response to erastin therapy, a pseudotargeted metabolomics method was achieved on ultra-high performance liquid chromatography-hybrid triple quadrupole linear ion trap mass spectrometry (UHPLC-QTRAP MS), which was used to investigate metabolic changes between erastin-treated MGC-803 cells and the controls at different time points. We found that erastin induced tremendous impact on the metabolome of gastric cells by affecting key metabolic processes, such as cysteine and methionine metabolism, tryptophan metabolism, purine metabolism, glutathione biosynthesis, glycolysis and TCA cycle. Interestingly, S-adenosylmethionine, methionine, serine and cysteine were obviously increasing treads after erastin treatment, while S-adenosylhomocysteine and glutathione were always down-regulated up to 24 h. The results indicated that DNA methylation was activated and glutathione biosynthesis was blocked in erastin-treated MGC-803 gastric cells, highlighting the importance of erastin as a promising drug candidate for in vivo treatment of gastric tumor.

Accurate Detection of G-Series Agent Simulants by Pseudo-Multiple Reaction Monitoring on Miniature LIT-MS.

Rapid and accurate on-site detection of chemical warfare agents (CWAs) could defend military and civilian populations against current and emerging chemical weapons. With the development of ambient ionization and linear ion trap technology, the rapid and accurate quantitative determination method of CWAs based on direct ionization and multistage mass spectrometry has attracted widespread attention. In this study, a microliter electrospray ionization-miniature linear ion trap mass spectrometry (LIT-MS) instrument was designed and constructed, and the effects of quadrupole enhanced dipole resonance excitation on the resolution and sensitivity were investigated; consequently, the parameters of CWAs detection were optimized. Based on the broad time-frequency ion excitation technology, accurate multiple reaction monitoring (MRM) quantitative analysis of DMMP (G-series agent simulants, m/z 125 → m/z 93) was obtained. The linear correlation coefficient in the concentration range of 1 to 20 μg/mL could reach 99.02%, and the relative standard deviations (RSD) of continuous repeatability, interday repeatability, and intraday repeatability were all less than 10%. The results showed that the accurate pseudo-MRM detection method based on miniature linear ion trap mass spectrometry for CWAs detection was feasible.

Liquid chromatography-mass spectrometry-based strategy for systematic profiling of chemical components and associated quantitative analysis of quality markers in Qi-Wei-Tong-Bi oral liquid.

Qi-Wei-Tong-Bi oral liquid (QWTB), a famous Chinese medicine preparation composed of seven crude drugs has a good therapeutic effect on rheumatoid arthritis and is widely used in China.However, its chemical composition and quality control have not been comprehensively and systematically investigated. In this study, high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was employed for its chemical profiling. As a result, 100 components were chemically characterized. Additionally, high-performance liquid chromatography coupled with a quadrupole linear ion trap mass spectrometry method was developed to simultaneously quantify nine bioactive components (hyperoside, ononin, quercetin, sinomenine, magnoflorine, gallic acid, protocatechuic acid, monotropein, and cyclo-(Pro-Tyr)) in multiple-reaction monitoring mode. After successful validation in terms of linearity, precision, repeatability, and recovery, the assay method was applied for the determination of 10 batches of QWTB. The results showed that QWTB was enriched in sinomenine and magnoflorine with the highest amount up to hundreds or even thousands of µg/mL, while quercetin, ononin, cyclo-(Pro-Tyr), and hyperoside were much lower with the lowest content below 10µg/mL. This study work would help to reveal the chemical profiling and provide a valuable and reliable approach for quality evaluation and even pharmacodynamic material basis studies of QWTB.

Analysis for disulfide bonds in polypeptide sequences based on ultraviolet photodissociation combined with linear ion trap mass spectrometry

The analysis of dissociation products of disulfide bonds in peptide sequences has been increasingly applied in various fields. Ion dissociation is typically performed by tandem mass spectrometry, in which the overall molecular weight is determined during the first stage and the protein sequence and structure are obtained by dissociation during the second stage. However, conventional dissociation methods have some disadvantages, such as insufficient dissociation efficiency, and low product signals and varieties. Ultraviolet photodissociation (UVPD) is a rapid, efficient, and practical dissociation method for protein analysis, which excites the biomolecule skeleton and then directly excites the molecules, forming the excited states within microseconds. Although the development of mass spectrometer platforms coupled with UVPD has been reported to date, most of these studies have focused on the application of UVPD in mass spectrometry (MS). Discussions on the experimental setup for UVPD lasers, including the trigger process of the ultraviolet (UV) laser, the timing sequence of the entire dissociation and detection process, and their influence on dissociation, are limited. Therefore, an instrument platform was developed with a linear ion-trap mass spectrometer and an excimer laser to achieve UVPD by adjusting the laser trigger signal. The platform dissociated the disulfide bond of the amino acid sequence ARACAKA-ECG into two characteristic valence states (m/z = 498 and 332), and their highest intensities were obtained by optimizing the experimental conditions of the platform. The dissociation results of UVPD showed the characteristic peaks of ARACAKA (m/z 345) that were produced by disulfide bond cleavage, but these peaks were not detected by collision-induced dissociation (CID). Therefore, it was confirmed that the developed platform realized UVPD of the disulfide bond of the amino acid sequence of the polypeptide. Moreover, the developed platform provides a reference for the implementation of UVPD for peptide sequencing.

Improved analysis of folpet and captan in foods using liquid chromatography-triple quadrupole linear ion trap mass spectrometry: applying mass filtering, collision, and trapping conditions

Accurate and highly sensitive analysis of folpet and captan was accomplished using liquid chromatography-triple quadrupole linear ion trap mass spectrometry (LC-QqQIT) with selective ion mode; mass filtering, collision, and trapping condition. Dimensional mass spectrometry (MS3) parameters were optimized for the residue detection of folpet and captan in six food commodities (apples, tomatoes, sweet pepper, wheat flour, sesame seeds, and fennel seeds). The sample preparation method was based on the known QuEChERS protocol, except a mixture of acetonitrile/acetone was used for the sample extraction from the sesame seeds. The robustness and reliability of the developed MS3 method were demonstrated by performing a full validation, according to SANTE/11312/2021, at 0.01-0.25mg/kg. Recovery ranged from 83 to 118% with a relative standard deviation below 19% in all the tested commodities, and limits of quantifications (LOQs) were 0.01mg/kg in apples and tomatoes; 0.03mg/kg in sweet pepper; and 0.05mg/kg in wheat flour, sesame seeds, and fennel seeds. Monitoring results showed that about 90% of apples contained captan residue, and in sweet pepper, concentrations of captan and folpet as high as 1.57 and 0.97mg/kg were found, respectively. The novel developed MS3 method enabled more reliable identification of these commonly problematic fungicides at lower LOQs than previously reported methods.

LC-MS-based metabolite profiling of aqueous extract of Pergularia tomentosa L. and its anti-hyperglycemic effect.

In this study, to find scientific evidence for the traditional use of Pergularia tomentosa as an anti-diabetic remedy, the effects of its aqueous extract on streptozotocin-induced diabetes mellitus in rats were evaluated. Wistar rats were fasted overnight and diabetes mellitus was induced using streptozotocin (50 mg/kg body weight). The rats were randomly and equally divided into four groups (n=5): group I (normoglycaemic control), group II (diabetic rats), group III (diabetic rats treated with 200 mg/kg BW of an aqueous extract of P. tomentosa), group IV (normoglycemic rats treated with 200 mg/kg BW of an aqueous extract of P. tomentosa). Chemical profiling of the aqueous extract was carried out using liquid chromatography coupled with electrospray ionization and multiple-stage linear ion-trap and orbitrap high-resolution mass spectrometry (LC-ESI/LTQOrbitrap/MS/MS). In addition, the quantitative determination of the main cardenolides in the extract was carried out by an analytical approach based on LC coupled to tandem mass spectrometry with ESI source and hybrid triple quadrupole-linear ion trap mass analyzer (LC-ESI/QTrap/MS/MS). Aqueous extract of P. tomentosa showed a reasonable reduction in blood glucose level. Probably, the P. tomentosa effect on hyperglycemic and hyperlipidemic diabetic animals was associated with antioxidant properties, triglyceride levels, as well as liver enzymes. Meanwhile, LC-ESI/LTQOrbitrap/MS/MS analysis led to identification of double-linked cardenolides along with cardenolides and flavone glycosides as the main bioactive compounds. The extract decreased the glucose level and induced a beneficial effect on the lipid profile, probably due to the presence of cardenolide glycosides.

Cross-Platform Identification and Classification of Fentanyl Analogs by Tandem Mass Spectrometry (MS/MS)

The abuse of fentanyl and its analogs has caused a large number of deaths worldwide. Due to the rapid development of new fentanyl analogs, the standard mass spectral library is generally incomplete. The spectra obtained by different mass spectrometers by electrospray ionization (ESI) cannot be used across platforms, resulting in the hysteretic detection of novel fentanyl analogs. This paper reports a machine learning classification model based upon a hybrid similarity search. For the purpose of the identification of fentanyl analogs with different mass spectrometers, a mass spectral library based on the conserved fragmentation behavior (CFB) of fentanyl analogs was established. The results show that the identification accuracy of fentanyl analogs by two mass spectrometers is 100%, and the accuracy of classification model is 97.85%. Furthermore, the model may be applied to linear ion trap mass spectrometry (LIT-MS) and quadrupole time-of-flight mass spectrometry (Q-TOF-MS) with classification accuracies of 100 and 98.17%, respectively. This study provides promising technical support for the real-time and cloud computing detection of unknown fentanyl analogs.

Comparative pharmacokinetic study of nine bioactive components in osteoarthritis rat plasma using ultra-performance liquid chromatography-tandem mass spectrometry after single and combined oral administration of Epimedii Folium and Chuanxiong Rhizoma extracts.

The herb pair Epimedii Folium-Chuanxiong Rhizoma (EF-CR), derived from the classical traditional Chinese medicine 'Xian Ling Pi San', has a distinctive compatibility therapeutic profile and is clinically safe and effective. This study aimed to investigate and compare the pharmacokinetic characteristics of nine analytes in osteoarthritis (OA) rat plasma after the oral administration of EF, CR or a combination of these two herbs. We developed an ultra-performance liquid chromatography method coupled with quadrupole linear ion-trap mass spectrometry to simultaneously quantify and assess the pharmacokinetics of icariin, epimedin A, epimedin B, epimedin C, icariside I, icariside II, ferulic acid, ligustilide and senkyunolide A of the EF-CR pair in the plasma of osteoarthritic rats. The pharmacokinetic parameters showed that the absorption of multiple components was significantly enhanced and residence time was prolonged in the EF-CR group (P < 0.05) compared to the single-herb group. These parameters revealed that the combination of EF and CR exhibited synergistic effects of the nine bioactive components, suggesting the potential application of the EF-CR combination for the treatment of OA.

Plasma proteome responses in zebrafish following λ-carrageenan-Induced inflammation are mediated by PMN leukocytes and correlate highly with their human counterparts.

Regulation of inflammation is a critical process for maintaining physiological homeostasis. The λ-carrageenan (λ-CGN) is a mucopolysaccharide extracted from the cell wall of red algae (Chondrus crispus) capable of inducing acute intestinal inflammation, which is translated into the production of acute phase reactants secreted into the blood circulation. However, the associated mechanisms in vertebrates are not well understood. Here, we investigated the crucial factors behind the inflammatory milieu of λ-CGN-mediated inflammation administered at 0, 1.75, and 3.5% (v/w) by i.p. injection into the peritoneal cavity of adult zebrafish (ZF) (Danio rerio). We found that polymorphonuclear leukocytes (neutrophils) and lymphocytes infiltrating the ZF peritoneal cavity had short-term persistence. Nevertheless, they generate a strong pattern of inflammation that affects systemically and is enough to produce edema in the cavity. Consistent with these findings, cell infiltration, which causes notable tissue changes, resulted in the overexpression of several acute inflammatory markers at the protein level. Using reversed-phase high-performance liquid chromatography followed by a hybrid linear ion-trap mass spectrometry shotgun proteomic approach, we identified 2938 plasma proteins among the animals injected with PBS and 3.5% λ-CGN. First, the bioinformatic analysis revealed the composition of the plasma proteome. Interestingly, 72 commonly expressed proteins were recorded among the treated and control groups, but, surprisingly, 2830 novel proteins were differentially expressed exclusively in the λ-CGN-induced group. Furthermore, from the commonly expressed proteins, compared to the control group 62 proteins got a significant (p < 0.05) upregulation in the λ-CGN-treated group, while the remaining ten proteins were downregulated. Next, we obtained the major protein-protein interaction networks between hub protein clusters in the blood plasma of the λ-CGN induced group. Moreover, to understand the molecular underpinnings of these effects based on the unveiled protein sets, we performed a bioinformatic structural similarity analysis and generated overlapping 3D reconstructions between ZF and humans during acute inflammation. Biological pathway analysis pointed to the activation and abundance of diverse classical immune and acute phase reactants, several catalytic enzymes, and varied proteins supporting the immune response. Together, this information can be used for testing and finding novel pharmacological targets to treat human intestinal inflammatory diseases.

Q value and parent energy optimization using a low-voltage ionization approach increases resolution in linear ion trap mass spectrometry.

In this work, the isolation step in the linear ion trap was performed using different "q values" conditions at a low collision-induced dissociation (CID) energy leading to the parent ion resolution improvements, reasonably due to better ion energy distribution. According to the results, we obtained a greater resolution and mass accuracy operating in both traditional electrospray and low voltage ionization near the q value =0.778 and with a CID energy of 10%. This effect was evaluated with low-molecular-mass compounds (skatole and arginine). The proposed optimization yielded a superior instrument performance without adding technological complexity to mass spectrometry analyses.

Systematic Qualitative and Quantitative Analyses of Wenxin Granule via Ultra-High Performance Liquid Chromatography Coupled with Ion Mobility Quadrupole Time-of-Flight Mass Spectrometry and Triple Quadrupole-Linear Ion Trap Mass Spectrometry.

Wenxin granule (WXG) is a popular traditional Chinese medicine (TCM) preparation for the treatment of arrhythmia disease. Potent analytical technologies are needed to elucidate its chemical composition and assess the quality differences among multibatch samples. In this work, both a multicomponent characterization and quantitative assay of WXG were conducted using two liquid chromatography–mass spectrometry (LC-MS) approaches. An ultra-high performance liquid chromatography–ion mobility quadrupole time-of-flight mass spectrometry (UHPLC/IM-QTOF-MS) approach combined with intelligent peak annotation workflows was developed to characterize the multicomponents of WXG. A hybrid scan approach enabling alternative data-independent and data-dependent acquisitions was established. We characterized 205 components, including 92 ginsenosides, 53 steroidal saponins, 14 alkaloids, and 46 others. Moreover, an optimized scheduled multiple reaction monitoring (sMRM) method was elaborated, targeting 24 compounds of WXG via ultra-high performance liquid chromatography–triple quadrupole linear ion trap mass spectrometry (UHPLC/QTrap-MS), which was validated based on its selectivity, precision, stability, repeatability, linearity, sensitivity, recovery, and matrix effect. By applying this method to 27 batches of WXG samples, the content variations of multiple markers from Notoginseng Radix et Rhizoma (21) and Codonopsis Radix (3) were depicted. Conclusively, we achieved the comprehensive multicomponent characterization and holistic quality assessment of WXG by targeting the non-volatile components.

Fluoropyrimidine Bioactivation and Metabolism by the Gut Microbiome

Despite decades of research into why populations of cancer patients differentially respond to the same treatment, variation in response to therapy regimens remains a significant challenge in the oncology field. However, our understanding of the causal mechanisms of interpatient variability remains lacking; up to 35% of patients require dose adjustments and 10% of patients are removed from the fluoropyrimidine capecitabine altogether. This research seeks to further our understanding of the microbiome’s role in fluoropyrimidine treatment by identifying gut bacterial strains responsible for capecitabine activation as well as biochemically characterizing drug inactivating enzymes from the human gut microbiome. Growth curve data show that knockouts of bacterial enzymes homologous to mammalian enzymes known to be involved in capecitabine metabolism increase bacterial resistance to capecitabine. Additionally, an unbiased transposon mutagenesis screen identifies enzymes known to increase resistance as well as enzymes both within and outside of nucleotide metabolism. These two pieces of data suggest that bacteria have the capacity to metabolize capecitabine, upending the paradigm that activation of this prodrug happens exclusively in the liver and tumor. Confirmation of these metabolites with high resolution triple quadrupole linear ion trap mass spectrometry is ongoing. Separately, previous studies indicate that gut bacteria are capable of degrading 5‐fluorouracil, however it is not clear how efficient these pathways are or to what extent they occur in the host. Enzyme kinetics of homologues of this enzyme within the microbiome show that degradative reaction for uracil is essentially irreversible. Additionally, this enzymatic characterization has identified the non‐enzymatic enantiomer of the degraded fluoropyrimidine as a potential inhibitor for this enzyme, which might allow for co‐dosing and inhibition of bacterial metabolism. Metagenomic sequencing of the degradative enzymes within patient samples is ongoing and will potentially reveal the main drivers of this activity in patients. These avenues of research will uncover new bacterial metabolism pathways of xenobiotics, compare these metabolic pathways between microbiota and host, and have the potential to lead to new advances in disrupting microbial metabolism of chemotherapeutics.

Simultaneous Determination of RDX and HMX in Rat Plasma by LC-MS/MS and its Applications.

Background: 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) can cause serious toxicity problems in humans and animals, but direct analyses of RDX and HMX in biological samples are very limited. A rapid and efficient liquid chromatography-electrospray quadrupole linear ion trap mass spectrometry (LC-MS/MS) method suitable for the simultaneous determination of RDX and HMX in rat plasma after intravenous administration of two nitramine compound mixed solutions has been developed. Methods: Plasma samples were pretreated with one-step protein precipitation, the plasma consumption is as low as 100 μl. RDX, HMX, and internal standard mycophenolic acid were eluted for 8.0 min on a reversed-phase C18 analytical column with a water/acetonitrile mixture as the mobile phase. An electrospray ionization (ESI) source was applied and operated in negative ion mode. The optimized mass transition ion pairs (m/z) monitored for RDX, HMX, and internal standard mycophenolic acid were m/z 284.1→61.7, m/z 331.0→108.8, and m/z 319.2→191.1, respectively. Results: The detection ranges of both RDX and HMX in plasma were 5.00–200.00 ng⋅ml−1 with an LOD of 1.00 ng⋅ml−1. The extraction recoveries of RDX and HMX were 60.04 ± 4.18% and 79.57 ± 3.35%, respectively. The precision and accuracy met the requirements, and the method was stable under all tested conditions. Conclusion: The present method is miniaturized, effective, portable, rapid and can be easily used for simultaneous quantification of RDX and HMX in rat plasma.

Simultaneous determination of 36 hypotensive drugs in fingerprints by ultra performance liquid chromatography-triple quadrupole composite linear ion trap mass spectrometry

指印中蕴含着供体摄入成分等相关信息,通过对其分析可对供体进行特征刻画,从而为案件侦查提供线索,指印分析也可用于药物摄入的定性检测,因此检验指印中的降压药具有重要的实际应用价值。建立了超高效液相色谱-三重四极杆复合线性离子阱质谱(UPLC-Q-TRAP/MS)同时检测指印中36种降压药的方法。前处理方法采用沉淀蛋白法,使用3×3 cm滤纸采集指印,将滤纸剪碎置于2 mL塑料离心管中,加入0.50 mL甲醇,涡旋混合1 min,超声振荡3 min,取出后以12000 r/min离心5 min,取上清液进样分析。采用ACQUITY UPLC® BEH C18柱(100 mm×3.0 mm, 1.7 μm)分离,以0.01%甲酸水溶液和甲醇作为流动相进行梯度洗脱。质谱分析采用可编程多反应监测-信息关联采集-增强子离子(SMRM-IDA-EPI)扫描方式,在高灵敏度分析的同时进行二级谱库检索,增加定性结果的准确性。36种药物在0.05~50.00 ng/fingerprint范围内线性关系良好,相关系数(r)大于0.99,检出限和定量限分别为0.001~0.045 ng/fingerprint和0.002~0.050 ng/fingerprint,在0.25、2.50、25.00 ng/fingerprint 3个加标水平下的基质效应为79.0%~119.2%,回收率为79.3%~116.2%,日内精密度为0.2%~18.3%,日间精密度为1.6%~19.1%。使用该方法检测了87名高血压患者指印中的降压药,大部分样本中可检出其所服用的药物。该方法操作简单,灵敏度高,选择性好,适用于指印中降压药的筛查检验。

Multiclass Comparative Analysis of Veterinary Drugs, Mycotoxins, and Pesticides in Bovine Milk by Ultrahigh-Performance Liquid Chromatography-Hybrid Quadrupole-Linear Ion Trap Mass Spectrometry.

A multiclass and multiresidue method for simultaneously screening and confirming veterinary drugs, mycotoxins, and pesticides in bovine milk was developed and validated with ultrahigh-performance liquid chromatography–hybrid quadrupole–linear ion trap mass spectrometry (UHPLC-Qtrap-MS). A total of 209 targeted contaminants were effectively extracted using an optimized QuEChERS method. Quantitative and qualitative confirmation were achieved simultaneously by multiple reaction monitoring–information-dependent acquisition–enhanced product ion (MRM-IDA-EPI) scan mode. The validation results exhibited a good sensitivity with the LOQs of 0.05–5 μg/kg, which was satisfactory for their MRLs in China or EU. The recoveries of in-house spiked samples were in the range of 51.20–129.76% with relative standard deviations (RSD) between replicates (n = 3) 0.82% and 19.76%. The test results of 140 milk samples from supermarkets and dairy farms in China showed that cloxacillin, aflatoxin M1, acetamiprid, and fipronil sulfone were found with lower concentrations. Combined with the residue results from the literature, penicillin G and cloxacillin (beta-lactams), enrofloxacin and ciprofloxacin (fluoroquinolones), and sulfamerazine (sulfonamides) were more frequently detected in different countries and need to receive more attention regarding their monitoring and control.

Rapid and selective determination of 9 nitrosamines in biological samples using ultra-high performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry.

A sensitive, selective and convenient method for the simultaneous determination of 9 nitrosamines (NAs) in biological samples was developed using isotope dilution ultra-high performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry (UPLC-QTRAP-MS). Multiple reaction monitoring-information dependent acquisition-enhanced product ion (MRM-IDA-EPI) scan mode was performed to eliminate false positive results, and the whole detection procedure was characterized by less time consuming and simple sample preparation. 9 NAs were separated through a T3 column with the gradient elution of acetonitrile and water, and detected by UPLC-QTRAP-MS with an atmospheric pressure chemical ionization (APCI) source in the positive mode. The quantitative analysis was carried out via the isotope internal standard method with a matrix calibration curve. Under the optimized conditions, good linearity for the 9 NAs was achieved in the range of 0.2-20 μg L-1 with correlation coefficients (r) higher than ≥0.9991, and the limits of detection and limits of quantitation were 0.02-0.1 μg L-1 (S/N = 3) and 0.06-0.3 μg L-1 (S/N = 10), respectively. Satisfactory recoveries ranging from 79.4% to 108.0% were obtained, and the precision of the proposed method, indicated by the relative standard deviations (RSDs), was 2.3-12.9%. The matrix effect study showed that NDMA, NMOR and NMEA presented a matrix suppression effect, NDPHA displayed a matrix enhancement effect, and the matrix effects of the other 5 analytes could be ignored. Real application of the developed method in 13 urine and 24 plasma samples demonstrated that NDBA, NPIP and NPYR occurred in both urine and plasma samples with the concentration of 0.038-0.60 μg L-1, while other NAs were not detected. Such a method was sensitive and selective, and could be applied to the rapid qualitative and quantitative analysis of the 9 NAs in biological samples.

Synthesis and analytical differentiation of a novel synthetic cathinone 1-(2,3-dihydro-1H-inden-5-yl)-2-(pyrrolidin-1-yl)butan-1-one (5-PPDI) and its regioisomers

The differentiation of a controlled drug from uncontrolled novel compounds related to regioisomers is a significant issue in forensics. The compound 1-(2,3-dihydro-1H-inden-5-yl)-2-(pyrrolidin-1-yl)butan-1-one (5-PPDI) is a novel synthetic cathinone first identified in 2015 as a new psychoactive substance. 5-PPDI is the indanyl analog of α-PBP, a typical synthetic cathinone, as well as the aliphatic ring analog of MDPBP, a synthetic cathinone with a heterocyclic ring. 5-PPDI can have three possible regioisomers, 1-(2,3-dihydro-1H-inden-1-yl)-2-(pyrrolidin-1-yl)butan-1-one (1-PPDI), 1-(2,3-dihydro-1H-inden-2-yl)-2-(pyrrolidin-1-yl)butan-1-one (2-PPDI), and 1-(2,3-dihydro-1H-inden-4-yl)-2-(pyrrolidin-1-yl)butan-1-one (4-PPDI), differing by the substituted position of the alkyl side-chain. In this study, 5-PPDI and its three regioisomers were synthesized from commercially available precursor compounds and analyzed by gas chromatography/electron ionization–quadrupole mass spectrometry (GC/EI–Q-MS) and by liquid chromatography/electrospray ionization–linear ion trap mass spectrometry (LC/ESI–LIT–MS). The four PPDI isomers could be differentiated by GC/EI–Q-MS with three types of separation columns and by 2nd generation product ion spectra (MS3) analysis using ESI–LIT–MS.

Characterization of Mycobacterium tuberculosis Mycolic Acids by Multiple-Stage Linear Ion-Trap Mass Spectrometry.

Mycobacterium tuberculosis (Mtb) cells are known to synthesize very long chain (C60-90) structurally complex mycolic acids with various functional groups. In this study, we applied linear ion-trap (LIT) multiple-stage mass spectrometry (MSn), combined with high-resolution mass spectrometry to study the mechanisms underlying the fragmentation processes of mycolic acid standards desorbed as lithiated adduct ions by ESI. This is followed by structural characterization of a Mtb mycolic acid family (Bovine strain). Using the insight fragmentation processes gained from the study, we are able to achieve a near complete characterization of the whole mycolic acid family, revealing the identity of the α-alkyl chain, the location of the functional groups including methyl, methoxy, and keto groups along the meroaldehyde chain in each lipid species. This study showcased the power of LIT MSn toward structural determination of complex lipids in a mixture, which would be otherwise very difficult to define using other analytical techniques.

Determination of lipophilic marine biotoxins in shellfish foods by ultra performance liquid chromatography-hybrid triple quadrupole linear ion trap-mass spectrometry

An ultra performance liquid chromatography-hybrid triple quadrupole linear ion trap-mass spectrometry(UPLC-QqLIT-MS) was established for determination of lipophilic marine biotoxins in shellfish. And the 12 lipophilic marine biotoxins in shellfish were surveyed. The lipophilic marine biotoxins in homogenized shellfish were ultrasonically extracted by methanol in super-sonic instrument, and cleaned up by solid phase extraction of Strata-X column, and eluted with methanol(containing 0.3% ammonia water). The elution was diluted with water, and cleaned by 0.22 μm millipore filter. The filtrate was separated on a Waters ACQUITY UPLC BEH C_(18) column(150 mm×2.1 mm, 1.7 μm)by gradient elution in 12 minutes with acetronitrile-water(containing 0.01%(V/V) ammonia and 2 mmol/L ammonium formate) as mobile phase, and detected by ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS), identified by electrospray ionization(ESI) in simultaneous scanning mode of positive and negative ions using multiple reaction monitoring, and quantified with external standards. Information dependent acquisition scan function(IDA) combined with enhanced production scan(EPI) was used to confirm the 12 lipophilic marine biotoxins. The calibration curves of 12 lipophilic marine biotoxins showed good linearity in the range of 0.5-50 μg/L with correlation coefficients were 0.9984-0.9999.The detection limits of the method were 0.15-0.29 μg/kg. The recoveries of three spiking levels ranged from 80.0% to 116.0%, and the relative standard deviation(RSD) were 0.6%-6.4%(n=7). The method for determination of 12 lipophilic marine biotoxins in shellfish by UPLC-QqLIT-MS was of operation convenience, less interference from impurities and good accuracy, which could meet the requirements for the determination of 12 lipophilic marine biotoxins residues in sea foods.

Toxic plants-Detection of colchicine in a fast systematic clinical toxicology screening using liquid chromatography-mass spectrometry.

Colchicum autumnale, which can be mistaken for Allium ursinum, contains the alkaloid colchicine potentially leading to life-threatening up to fatal intoxications. We report two cases of acute intoxications with unexplained circumstances. Using the authors' systematic screening approaches, colchicine could be detected in blood plasma and urine samples using liquid chromatography coupled to linear ion trap mass spectrometry (LC-ITMSn ) and high-resolution tandem mass spectrometry (LC-HRMS/MS). Metabolites of colchicine could be identified in urine for confirmation of screening results. Gas chromatography-mass spectrometry (GC-MS) analysis was also conducted, but colchicine could not be detected. Furthermore, colchicine concentration was estimated via LC-HRMS/MS in plasma samples. Results of the systematic screening indicated the ingestion of colchicine from both subjects. In both cases, the parent compound was detected in blood plasma and urine using the LC-HRMS/MS and LC-ITMSn system. An O-demethylation metabolite was identified in urine samples of both subjects using LC-HRMS/MS; the N-deacetylation product was also found in urine samples of both cases via LC-HRMS/MS and LC-ITMSn . The use of LC-ITMSn resulted only in the detection of the O-demethylation product in case 2. Plasma concentrations were estimated at 2.5ng/ml and 4.7ng/ml for cases 1 and 2, respectively. We demonstrated the detection of this highly toxic alkaloid in blood plasma and urine using a time-saving and reliable clinical systematic screening. Furthermore, we identified metabolites of colchicine being rarely discussed in literature, which can be used as additional screening targets.