Py–GC–MS examination of intermediates in the vapor from rapid pyrolysis of larch wood and its model components

Py–GC–MS was used to examine the components of vapor from rapid pyrolysis of larch wood and its model components, i.e. example cellulose, xylan, and lignin, and their mixture in accordance with the proportion of the components in larch wood. In this study, a total of 97 compounds in 12 categories were identified in the pyrolysis vapor and were compared. It was found that the most abundant chemical species in these five types of pyrolysis vapor were different. Saccharides and ketones were the major compounds in the pyrolysis vapor from microcrystalline cellulose and xylan, respectively, whereas the most abundant compounds in the pyrolysis vapor from alkaline lignin were sulfur compounds and phenols. Saccharides and ketones were major components of the pyrolysis vapor from MMC, whereas the main compounds in the pyrolysis vapor from larch wood were ketones, phenols, aldehydes, and saccharides. The different composition of the pyrolysis vapor from larch wood and its model mixture was explained on the basis of their different structural frameworks and the non-structural components of larch wood. It was also concluded that the presence of non-structural components, including extractives and ash, affect the pyrolysis reaction of larch wood. Nevertheless, the detailed patterns of this process must be further studied.     

Essential oil from Rhaponticum acaule L. roots: Comparative study using HS-SPME/GC/GC–MS and hydrodistillation techniques

The composition of essential oil extracted from Rhaponticum acaule L. roots growing wild in Algeria was studied by hydrodistillation (HD) and by Head-Space Solid Phase Micro-Extraction (HS-SPME). Quantitative but not qualitative differences have been found in the chemical composition of both analysed samples depending on the extraction method. However, the oil obtained from R. acaule roots shows that aliphatic alcohols were found to be the major class (69.2%), followed by the terpenes (5.5%), alkenes (5.2%) and alkynes (4.0%). In both cases the analysis were carried out using Gas Chromatography (GC) and Gas Chromatography–Mass Spectrometry (GC–MS). Our study shows that HS-SPME extraction could be considered as an alternative technique for the isolation of volatiles from plant. 25 components were identified in oil vs. 39 in the HS-SPME. However the oil composition of roots was mainly represented by a variety of aliphatic hydrocarbons (alcohols, aldehydes and ketones) and terpenes which are known for their antimicrobial activities.     

Marker peptide combination for source identification of gelatins obtained from Equidae hides by LC–MS/MS detection

Gelatin, which is a soluble, natural polymer produced by partial hydrolysis of collagens, has been extensively used in food and pharmaceuticals. Donkey-hide gelatin is a well-known traditional Chinese medicine. The certification of donkey-hide gelatin is one of the most concerned issues for consumers. Currently, the source identification of the homologous family species, including donkey, horse and their hybrids, remains a major challenge. Here, three peptides (SGQPGTVGPAGVR, GASGPAGVR and GATGPAGVR) of the equine family species were screened using high-resolution LC-MS. The combination of these three peptides has been used as a high-performance marker in LC-MS/MS to identify the animal source (donkey, horse, and their hybrids) of donkey-hide-gelatin-containing products. Horse-hide gelatin and hybrid-hide gelatin can be detected in gelatin-based products even at very low percentages (0.05% and 0.10%, respectively). The marker peptide combination method is useful for source identification of homologous family species and is not only highly sensitive but also rapid.     

Photochemical degradation study of polyvinyl acetate paints used in artworks by Py–GC/MS

Photochemical degradation of commercial polyvinyl acetate (PVAc) homopolymer and PVAc paints mixed with burnt umber, cobalt blue, cadmium red dark, nickel azo yellow and titanium white commonly used for artworks were studied by pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Py–GC/MS with single-shot technique was used for the characterization of the thermal degradation of PVAc at different temperatures, while the double-shot technique of Py–GC/MS was used to reveal the differences in the specimens before and after UV ageing, including the changes of detectable amounts of deacetylation product – acetic acid and plasticizers such as diethyl phthalate (DEP). Furthermore, the relative concentration of the pyrolysis products of the paint samples could be measured and compared in the second step of the double-shot Py–GC/MS, which are highly dependent on the presence of pigments and the ageing status of PVAc paints.     

A Novel Derivatization Method for Separation of Sarcosine from Isobaric l-Alanine in Human Urine by GC–MS

Sarcosine, an isomer of l-alanine, has been recently proposed as a potential biomarker for prostate cancer risk and aggressiveness, while some studies debated its importance. As both sarcosine and l-alanine are present in human urine, it is a great challenge to separate and accurately quantify these isobaric (i.e., same m/z) compounds by chromatographic separation and mass spectrometric detection. In this study, we developed a novel 1,3-dipolar cycloaddition derivatization method that resolves sarcosine from l-alanine and allows accurate quantification of sarcosine in human urine by gas chromatography–mass spectrometry (GC–MS). This novel derivatization approach was specific to sarcosine only, while the common silylanization method resulted in overlapped derivates of both sarcosine and l-alanine. The derivatization conditions, including reagent amount, reaction temperature and time, were optimized. The method developed here has excellent precision (relative standard deviation <4.7 %, n = 5), good linearity (slope = 0.2408; r ² = 0.9996, 0.1–100 μg mL^?1), and a low limit of detection in human urine (0.15 ng mL^?1). Application of this analytical method to urine samples spiked with standard sarcosine indicates that it is a robust and powerful alternative for resolving and quantifying sarcosine from l-alanine isomer in human urine by GC–MS.     

NACE–ESI-MS/MS method for separation and characterization of phosphorylation and acylation isomers of lipid A

Lipid A represents a heterogeneous group of bacterial outer membrane phosphoglycolipids, which play a major role in the pathogenesis of Gram-negative sepsis. The number and position of phosphoryl and acyl groups in lipid A molecules are key structural determinants in their bioactivities. In this study, a NACE–ESI-MS/MS method was developed for the simultaneous analysis of lipid A isomers possessing a different degree of phosphorylation and acylation. Various C4’- and C1-monophosphorylated lipid A isobars, as well as acylation isomers, were baseline separated within 43 min in a separation medium of methanol/dichloromethane/triethylamine/acetic acid 60:40:1.08:0.36 (v/v/v/v). Both normal and reverse CE polarities could be applied for proper detection of the analytes owing to the combination of a suction effect caused by the nebulizer gas at the outlet end of the capillary and external pressure applied on the inlet vial. The separated lipid A species could be identified unequivocally by their characteristic fragmentation patterns through CID performed in both negative- and positive-ionization modes. The uniqueness of the NACE–ESI-MS/MS method lies in its simplicity and reliability for proving the phosphorylation isomerism (C1 or C4’) and acylation pattern of native lipid A species or those designed for therapeutic applications.     

A fast and effective routine method based on HS-SPME–GC–MS/MS for the analysis of organotin compounds in biota samples

This work validated an automated, fast, and low solvent- consuming methodology suited for routine analysis of tributyltin (TBT) and degradation products (dibutyltin, DBT; monobutyltin, MBT) in biota samples. The method was based on the headspace solid-phase microextraction methodology (HS-SPME), coupled with gas chromatographic separation and tandem mass-spectrometry (GC–MS/MS). The effectiveness of the matrix-matched signal ratio external calibration was tested for quantification purposes. The exclusion of matrix influences in the calibration curves proved the suitability of this versatile quantification method. The method detection limits obtained were of 3 ng Sn g⁻¹ dw for all the analytes. The analysis of references materials showed satisfying accuracy under optimum calibration conditions (% recovery between 87–111%; |Z-scores|<2). The repeatability RSD% and intra-laboratory reproducibility RSD% were lower than 9.6% and 12.6%, respectively. The work proved the remarkable analytical performances of the method and its high potential for routine application in monitoring organotin compounds (OTC).     

A novel LC–MS/MS method for the determination of ziritaxestat in rat plasma and its pharmacokinetic study

Ziritaxestat is a first-in-class autotoxin inhibitor. The purpose of this study was to develop a liquid chromatography/electrospray ionization tandem mass spectrometric (LC–MS/MS) method for the determination of ziritaxestat in rat plasma. The plasma sample was deproteinated using acetonitrile and then separated on an Acquity BEH C₁₈ column with water containing 0.1% formic acid and acetonitrile as mobile phase, which was delivered at 0.4 ml/min. Ziritaxestat and the internal standard (crizotinib) were quantitatively monitored with precursor-to-product transitions of m/z 589.3 > 262.2 and m/z 450.1 > 260.2, respectively. The total running time was 2.5 min. The method showed excellent linearity over the concentration range 0.5–2000 ng/ml, with correlation coefficient >0.9987. The extraction recovery was >82.09% and the matrix effect was not significant. Inter- and intra-day precisions (RSD) were <11.20% and accuracies were in the range of −8.50–7.45%. Ziritaxestat was demonstrated to be stable in rat plasma under the tested conditions. The validated LC–MS/MS method was successfully applied to study the pharmacokinetic profiles of ziritaxestat in rat plasma after intravenous and oral administration. Pharmacokinetic results demonstrated that ziritaxestat displayed a short half-life (~3 h) and low bioavailability (20.52%).     

A validated HPTLC method for quantification of cordifolioside A, 20-β-hydroxyecdysone and columbin with HPTLC–ESI–MS/MS characterization in stems of Tinospora cordifolia

JPC – Journal of Planar Chromatography – Modern TLC - The objective of the present work was to develop a simple, specific, and fast high-performance thin-layer chromatographic (HPTLC)...     

A Hexagonally Ordered Nanoporous Silica-Based Fiber Coating for SPME of Polycyclic Aromatic Hydrocarbons from Water Followed by GC–MS

A highly porous fiber coating material was prepared and functionalized with 3-amino propyl triethoxysilane (APTES) on hexagonally ordered nanoporous silica (SBA-15). Applicability of this coating was assessed employing a laboratory made solid-phase microextraction (SPME) device and gas chromatography–mass spectrometry for the simultaneous sampling and determination of trace polycyclic aromatic hydrocarbons (PAHs) from aqueous sample solutions. A one at the time optimization strategy was applied to investigate and optimize important extraction parameters such as extraction temperature, extraction time, ionic strength and sonication time. In the optimum conditions, the relative standard deviations for deionized water, spiked with selected PAHs were between 3.3 and 7.7% (n = 3), and detection limits for the studied compounds were 4.2 and 26.1 pg mL⁻¹. No significant change was observed in the extraction efficiency of the new SPME fiber, over 50 extractions. The proposed method was successfully applied to the extraction and determination of PAHs in the waste water samples.

     

A validated LC–MS/MS method for the quantification of capivasertib in dog plasma: Application to its pharmacokinetics study

In this study, a simple and reliable liquid chromatography tandem mass spectrometric method was first developed for the determination of capivasertib in dog plasma with ipatasertib as internal standard. The plasma samples were deproteinated using acetonitrile. An Acquity BEH C₁₈ column (1.7 μm, 2.1 × 50 mm) maintained at 40°C was used for chromatographical separation, with water containing 0.1% formic acid and acetonitrile as mobile phase. Multiple reaction monitoring transitions were m/z 429.2 > 135.1 for capivasertib and m/z 458.2 > 387.2 for ipatasertib, respectively. Excellent linearity was achieved in the concentration range of 1–1,000 ng/ml with a correlation coefficient of >0.9981. The lower limit of quantification was 1 ng/ml. The extraction recovery of capivasertib from dog plasma was >85.81% and no significant matrix effect was found. The intra- and inter-day precision was <9.58% and the accuracy ranged from −10.60% to 12.50%. The validated method was further applied to the pharmacokinetic study of capivasertib in dog plasma after single oral (5 mg/kg) and intravenous (1 mg/kg) administrations. The results revealed that capivasertib was rapidly absorbed into plasma with good bioavailability (47.04%) and low clearance.     

Characterization of the chemical differences between solvent extracts from Pu-erh tea and Dian Hong black tea by CP–Py–GC/MS

Solvent extracts from a type of Pu-erh tea and Dian Hong black tea were characterized by Curie-point pyrolysis–gas chromatography–mass spectroscopy (CP–Py–GC/MS). The ethyl-acetate extracts from both teas showed similar CP–Py–GC/MS results, with main pyrolytic products of carbon dioxide, caffeine, o-phenols, and phthalate esters. During pyrolysis, the n-butanol extract from Pu-erh tea formed carbon dioxide (38.92% of total pyrolytic products), alkaloids (49.7%), and nitrogen oxides (8.38%), as well as a small fraction of esters. The n-butanol extract from Dian Hong tea formed mainly alcohols, amines, esters, phenols, carboxylic acids, and alkaloids. The raw theabrownin extracts (ethanol precipitates) from the two teas produced substantially different CP–Py–GC/MS results. The raw theabrownin extract from Pu-erh tea formed mostly carbon dioxide during pyrolysis, whereas the counterpart extract from Dian Hong tea formed mainly carbon dioxide (48.23%) and nitrogen oxides (35.39%). The 3.5–100 kDa fractions separated from the theabrownin extracts of the two teas showed similar CP–Py–GC/MS results, whereas the fractions <3.5 kDa and >100 kDa formed substantially different pyrolytic products. These results showed that solvent extracts from Pu-erh tea and Dian Hong tea had substantially different chemical compositions and structures. The study suggested that CP–Py–GC/MS can be used to effectively identify chemical differences between tea extracts.     

A post-modification approach to independent compo-nent analysis for resolution of overlapping GC/MS signals: from independent components to chemical components

Independent component analysis (ICA) has demonstrated its power to extract mass spectra from over-lapping GC/MS signal. However, there is still a problem that mass spectra with negative peaks at some m/z will be obtained in the resolved results when there are overlapping peaks in the mass spectra of a mixture. Based on a detail theoretical analysis of the preconditions for ICA and the non-negative property of GC/MS signals, a post-modification based on chemical knowledge (PMBK) strategy is pro-posed to solve this problem. By both simulated and experimental GC/MS signals, it was proved that the PMBK strategy can improve the resolution effectively.     

Characterization of chemical compositions by a GC–MS/MS approach and evaluation of antioxidant activities of essential oils from Cinnamomum reticulatum Hay,Leptospermum petersonii Bailey,and Juniperus formosana Hayata

Essential oils (EOs) are one type of the most significant plant metabolites. Limited works have been conducted on EOs extracted from Cinnamomum reticulatum Hay (CREO), Leptospermum petersonii Bailey (LPEO), and Juniperus formosana Hayata (JFEO), which belong to the Lauraceae, Cupressaceae, and Myrtaceae families, respectively. The present work aimed to characterize and compare EOs chemical compositions of the three aromatic plant species and simultaneously evaluate their antioxidant activities. Using GC–MS/MS techniques, totally 135 volatile organic compounds (VOCs) belonging to nine chemical classes were detected, with 93, 102 and 116 VOCs from and 7, 8 and 16 VOCs unique to CREO, LPEO and JFEO, respecively, and 72 VOCs common to all the three EOs. The main compound identified both in LPEO and JFEO was (?)-bornyl acetate (20.23% and 28.40%, respectively), and the dominated compounds in CREO were L-α-terpineol (16.21%) and 1,2,3,4-tetrahydro-1,6-dimethyl-4-(1-methylethyl)naphthalene (11.68%), all accounting for more than 20% of their total contents. An in-depth dissection of major chemical compositions of the three EOs found that three VOCs were newly identified and biological functions of four VOCs were not yet reported previously. In addition, higher antioxidant capacities, measured with DPPH and ABTS assays, were exhibited in JFEO (IC50 8.37 ± 2.98 and 0.53 ± 3.80 mg/ml, respectively) and in LPEO (IC50 13.93 ± 2.11 and 1.32 ± 0.97 mg/ml) than in CREO (IC50 250.58 ± 1.48 and 4.81 ± 3.23 mg/ml), which may be due to CREO contained more esters and less aromatics than the other two EOs.     

A validated LC–MS/MS method for simultaneous quantification of simvastatin and simvastatin acid in beagle plasma: Application to an absolute bioavailability study

A highly sensitive LC–MS/MS method for simultaneous detection of both simvastatin (SV) and simvastatin acid (SVA) in beagle plasma was developed and successfully applied to an absolute bioavailability study. Lovastatin (LV) was used as internal standard (IS). The analysis was performed using electrospray ionization and selective reaction monitoring in positive mode at m/z 441.0 → 325.0 for SV, 459.0 → 343.0 for SVA and 427.0 → 325.0 for the IS, respectively. The assay procedure involved a simple liquid–liquid extraction of SV, SVA and LV from beagle plasma into methyl tert-butyl ether. Separation of SV, SVA and the IS was achieved on a Shim-pack VP-ODS column (150 × 2.0 mm, 5 μm) with a binary gradient solvent system of 0.1% formic acid in water and methanol (15:85, v/v) as the mobile phase. The method was validated over the range of 0.25–500 ng/ml for SV (r² ≥ 0.9923) and 0.24–481.23 ng/ml for SVA (r² ≥ 0.9987). The results of method validation for accuracy, precision, extraction recovery, matrix effect and stability were within the acceptance criteria. The values of absolute bioavailability of SV and SVA in beagles were 2.97 and 25.40%, respectively. It is the first study developed for the measurement of absolute bioavailability of SV and SVA acid in beagles.     

A rapid UHPLC–MS/MS method for the quantification of ARQ531 in rat plasma: Validation and its application to a pharmacokinetic study

A simple and sensitive ultra-high performance liquid chromatography–tandem mass spectrometric (UHPLC–MS/MS) method was developed and validated for the determination of ARQ531, a Bruton’s tyrosine kinase inhibitor in rat plasma. After protein precipitation with acetonitrile, the samples were separated on a UPLC BEH C₁₈ column with 0.1% formic acid in water and acetonitrile as mobile phase at a flow rate of 0.4 ml/min. The mass detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring with precursor-to-product ion transitions of m/z 479.1 > 365.1 and m/z 441.2 > 138.1 for ARQ531 and internal standard, respectively. Good linearity (correlation coefficient > 0.9988) was achieved over the concentration range of 0.5–1,000 ng/ml and the lower limit of quantitation was 0.5 ng/ml. The accuracy ranged from −13.50 to 11.35% and the precision was <8.87%. The extraction recovery was >85.56%. ARQ531 was demonstrated to be stable under the tested conditions. The validated method was further applied to a pharmacokinetic study of ARQ531 in rats after intravenous (1 mg/kg) and oral (1, 3 and 10 mg/kg) administration. The results demonstrated that ARQ531 displayed linear pharmacokinetic profiles over the oral dose range of 1–10 mg/kg and good oral bioavailability (>50%).     

A dried blood spot assay with HPLC–MS/MS for the determination of larotrectinib in mouse blood and its application to a pharmacokinetic study

Larotrectinib is a first-generation tropomyosin kinase inhibitor, approved for the treatment of solid tumors. In this paper, we present a validated dried blood spot (DBS) method for the quantitation of larotrectinib from mouse blood using HPLC–MS/MS, which was operated under multiple reaction monitoring mode. To the DBS disc cards, acidified methanol enriched with internal standard (IS; enasidenib) was added and extracted using tert-butyl methyl ether as an extraction solvent with sonication. Chromatographic separation of larotrectinib and the IS was achieved on an Atlantis dC₁₈ column using 10 mm ammonium formate–acetonitrile (30:70, v/v) delivered at a flow-rate of 0.80 ml/min. Under these optimized conditions, the retention times of larotrectinib and the IS were ~0.93 and 1.37 min, respectively. The total run time was 2.50 min. Larotrectinib and the IS were analyzed using positive ion scan mode and parent–daughter mass to charge ion (m/z) transitions of 429.1 → 342.1 and 474.1 → 267.1, respectively, were used for the quantitation. The calibration range was 1.06–5,080 ng/ml. No matrix effect or carryover was observed. Hematocrit did not influence DBS larotrectinib concentrations. All of the validation parameters met the acceptance criteria. The applicability of the validated method was shown in a mouse pharmacokinetic study.     

High-throughput characterization of sediment organic matter by pyrolysis–gas chromatography/mass spectrometry and multivariate curve resolution: A promising analytical tool in (paleo)limnology

Molecular-level chemical information about organic matter (OM) in sediments helps to establish the sources of OM and the prevalent degradation/diagenetic processes, both essential for understanding the cycling of carbon (C) and of the elements associated with OM (toxic trace metals and nutrients) in lake ecosystems. Ideally, analytical methods for characterizing OM should allow high sample throughput, consume small amounts of sample and yield relevant chemical information, which are essential for multidisciplinary, high-temporal resolution and/or large spatial scale investigations. We have developed a high-throughput analytical method based on pyrolysis–gas chromatography/mass spectrometry and automated data processing to characterize sedimentary OM in sediments. Our method consumes 200 μg of freeze-dried and ground sediment sample. Pyrolysis was performed at 450 °C, which was found to avoid degradation of specific biomarkers (e.g., lignin compounds, fresh carbohydrates/cellulose) compared to 650 °C, which is in the range of temperatures commonly applied for environmental samples. The optimization was conducted using the top ten sediment samples of an annually resolved sediment record (containing 16–18% and 1.3–1.9% of total carbon and nitrogen, respectively). Several hundred pyrolytic compound peaks were detected of which over 200 were identified, which represent different classes of organic compounds (i.e., n-alkanes, n-alkenes, 2-ketones, carboxylic acids, carbohydrates, proteins, other N compounds, (methoxy)phenols, (poly)aromatics, chlorophyll and steroids/hopanoids). Technical reproducibility measured as relative standard deviation of the identified peaks in triplicate analyses was 5.5 ± 4.3%, with 90% of the RSD values within 10% and 98% within 15%. Finally, a multivariate calibration model was calculated between the pyrolytic degradation compounds and the sediment depth (i.e., sediment age), which is a function of degradation processes and changes in OM source type. This allowed validation of the Py–GC/MS dataset against fundamental processes involved in OM cycling in aquatic ecosystems.