Rapid quality assessment of Radix Aconiti Preparata using direct analysis in real time mass spectrometry

This study presents a novel and rapid method to identify chemical markers for the quality control of Radix Aconiti Preparata, a world widely used traditional herbal medicine. In the method, the samples with a fast extraction procedure were analyzed using direct analysis in real time mass spectrometry (DART MS) combined with multivariate data analysis. At present, the quality assessment approach of Radix Aconiti Preparata was based on the two processing methods recorded in Chinese Pharmacopoeia for the purpose of reducing the toxicity of Radix Aconiti and ensuring its clinical therapeutic efficacy. In order to ensure the safety and effectivity in clinical use, the processing degree of Radix Aconiti should be well controlled and assessed. In the paper, hierarchical cluster analysis and principal component analysis were performed to evaluate the DART MS data of Radix Aconiti Preparata samples in different processing times. The results showed that the well processed Radix Aconiti Preparata, unqualified processed and the raw Radix Aconiti could be clustered reasonably corresponding to their constituents. The loading plot shows that the main chemical markers having the most influence on the discrimination amongst the qualified and unqualified samples were mainly some monoester diterpenoid aconitines and diester diterpenoid aconitines, i.e. benzoylmesaconine, hypaconitine, mesaconitine, neoline, benzoylhypaconine, benzoylaconine, fuziline, aconitine and 10-OH-mesaconitine. The established DART MS approach in combination with multivariate data analysis provides a very flexible and reliable method for quality assessment of toxic herbal medicine.     

Rapid and nondestructive analysis of phthalic acid esters in toys made of poly(vinyl chloride) by direct analysis in real time single‐quadrupole mass spectrometry

In the European Community, selected phthalic acid esters (PAE) are restricted in their use for the manufacture of toys and childcare articles to a content of 0.1% by weight. As PAE are mainly used as plasticisers for poly(vinyl chloride) (PVC), a rapid screening method for PVC samples with direct analysis in real time ionisation and single‐quadrupole mass spectrometry (DART‐MS) was developed. Using the ions for the protonated molecules, a limit of detection (LOD) of 0.05% was obtained for benzyl butyl phthalate, bis(2‐ethylhexyl) phthalate and diisononyl phthalate, while for dibutyl phthalate, di‐n‐octyl phthalate and diisodecyl phthalate the LOD was 0.1%. Validation of identification by the presence of ammonium adducts and characteristic fragment ions was possible to a content of ≥1% for all PAE, except for benzyl butyl phthalate (≥5%). Based on the fragment ions, bis(2‐ethylhexyl) phthalate could clearly be distinguished from di‐n‐octyl phthalate, if the concentrations were ≥5% and ≥1% at measured DART helium temperatures of 130 and 310°C, respectively. The complete analysis of one sample only took about 8 min. At the generally used gas temperature of 130°C, most toy and childcare samples did not sustain damage if their shape fitted into the DART source. Copyright © 2009 John Wiley & Sons, Ltd.     

Efficient deep-blue light-emitting polyfluorenes based on 9,9-dimethyl-9H-thioxanthene 10,10-dioxide isomers

We have designed and synthesized a series of deep-blue light-emitting polyfluorenes, PF-27SOs and PF-36SOs, by introducing electron-deficient 9,9-dimethyl-9H-thioxanthene 10,10-dioxide isomers (27SO and 36SO) into the poly(9,9-dioctylfluorene) (PFO) backbone. Compared with PFO, the resulting polymers exhibit an equivalent thermal decomposition temperature (>415 °C), an enhanced glass transition temperature (>99 °C), a decreased lowest unoccupied molecular orbital energy level (E_LUMO) below −2.32 eV, a blue-shifted photoluminescence spectra in solid film with a maximum emission at ~422 nm, and a shoulder peak at ~445 nm. The resulting polymers also show blue-shifted and narrowed electroluminescence spectra with deep-blue Commission Internationale de L'Eclairage (CIE) coordinates of (0.16, 0.07) for PF-27SO20 and (0.16, 0.06) for PF-36SO30, compared with (0.17, 0.13) for PFO. Moreover, simple device based on PF-36SO30 achieves a superior device performance with a maximum external quantum efficiency (EQE_max = 3.62%) compared with PFO (EQE_max = 0.47%). The results show that nonconjugated 9,9-dimethyl-9H-thioxanthene 10,10-dioxide isomers can effectively perturb the conjugation length of polymers, significantly weaken the charge-transfer effect in donor–acceptor systems, substantially improve electroluminescence device efficiency, and achieve deep-blue light emission.     

Mass fragmentation study of the trimethylsilyl derivatives of arctiin,matairesinoside, arctigenin,phylligenin, matairesinol,pinoresinol and methylarctigenin: Their gas and liquid chromatographic analysis in plant extracts

The mass fragmentation patterns and the characteristic behavior of the trimethylsilyl (TMS) derivatives of the dibenzylbutyrolactone-type (arctiin, arctigenin, methylarctigenin, matairesinoside, matairesinol) and those of the diphenylperhydrofurotetrahydrofurane-type (phylligenin, pinoresinol) lignans, obtained by gas chromatography–mass spectrometry (GC–MS), were presented. It was shown that upon acidic hydrolysis the dibenzylbutyrolactone-type lignans are stable while the diphenylperhydrofurotetrahydrofurane-type ones decompose. As a novelty to the field we confirmed that the fragment species of the derivatized lignan glycosides, in the presence of excess hexamethyldisilazane, leaded to their in situ derivatization. Quantification of the selective fragment ions of the TMS derivatives by GC–MS, in respect of the ions found one by one, and concerning the selective fragment ions {SFI(s)} in total, provided acceptable reproducibilities, suitable for quantitation purposes: varying between 1.20% and 6.6% relative standard deviation percentages (RSD%). For characterization of the behavior of various type of lignans, analyses were performed with the untreated and with the trifluoroacetic acid hydrolyzed plant extracts, from the same sample, in parallel, both by GC–MS and by high performance liquid chromatography–mass spectrometry, working in the positive electron ionization mode (HPLC–ESPI-MS). The analysis of lignans in fruit and leaf extracts (obtained from the Arctium, Centaurea and Forsythia plants) was confirmed both by GC–MS and by HPLC–ESPI-MS. Our multicomponent system (including the identification and quantification of sugars, sugar alcohols, and several members of various homologous series of acids, anthraquinones and flavonoids) has been extended to the analysis of lignan glycosides and to the free lignans. Reproducibilities in the quantitation of lignans in plant matrices, as averages on GC and HPLC basis, varied between 0.9% and 11% (RSD). The distribution of the lignan constituents was presented for 5 Arctium, for 8 Centaurea and for 4 Forsythia plant extracts: the total of lignan contents varied between 0.42 and 87.9 mg/g, respectively.     

Direct analysis in real time (DART) mass spectrometry of nucleotides and nucleosides: elucidation of a novel fragment [C<Subscript>5</Subscript>H<Subscript>5</Subscript>O]<Superscript>+</Superscript> and its in-source adducts

Direct analysis in real time (DART) mass spectrometry is a recently developed innovative technology, which has shown broad applications for fast and convenient analysis of complex samples. Due to the ease of sample preparation, we have recently initiated an investigation of the feasibility of detecting nucleotides and nucleosides using the DART-AccuTOF instrument, which we will refer to as the DART mass spectrometer. Our experimental results reveal that the ions representing the intact molecules of nucleotides are not detectable in either positive-ion or negative-ion mode. Instead, all four natural nucleotides fragment in the DART ion source, and a common fragment ion, [C₅H₅O]⁺ (1), is observed, which is probably formed via multiple-elimination reactions. Interestingly, 1 can form adducts with nucleobases in different molar ratios in the DART ion source. In contrast to nucleotides, the ions representing the intact molecules of nucleosides are detected in both positive-ion and negative-ion mode using DART mass spectrometry. Surprisingly, the fragmentation pattern of nucleosides is different from that of nucleotides in the DART ion source. In the cases of nucleosides (under positive-ion conditions), the production of 1 is not observed, indicating that the phosphate group plays an important role for the multiple eliminations observed in the spectra of nucleotides. The in-source reactions described in the present work show the complexity of the conditions in the DART ion source, and we hope that our results illustrate a better understanding about DART mass spectrometry.     

Evaluation of ice‐tea quality by DART‐TOF/MS

DART (Direct Analysis in Real Time) coupled with Time‐of‐Flight Mass Spectrometry (TOF/MS) has been used for analyses of ice‐teas. The article focuses on quality and authenticity of ice‐teas as one of the most important tea‐based products on the market. Twenty‐one samples of ice‐teas (black and green) were analysed. Selected compounds of ice‐teas were determined: theobromine, caffeine, total phenolic compounds, total soluble solids, total amino acid concentration, preservatives and saccharides were determined. Fingerprints of DART‐TOF/MS spectra were used for comprehensive assessment of the ice‐tea samples. The DART‐TOF/MS method was used for monitoring the following compounds: citric acid, caffeine, saccharides, artificial sweeteners (saccharin, acesulphame K), and preservatives (sorbic and benzoic acid), phosphoric acid and phenolic compounds. The measured data were subjected to a principal components analysis. The HPLC and DART‐TOF/MS methods were compared in terms of determination of selected compounds (caffeine, benzoic acid, sorbic acid and saccharides) in the ice‐teas. The DART‐TOF/MS technique seems to be a suitable method for fast screening, testing quality and authenticity of tea‐based products. Copyright © 2015 John Wiley & Sons, Ltd.     

Quantitative analysis of phosphoric acid esters in aqueous samples by isotope dilution stir-bar sorptive extraction combined with direct analysis in real time (DART)-Orbitrap mass spectrometry

A novel hyphenated technique, namely the combination of stir bar sorptive extraction (SBSE) with isotope dilution direct analysis in real time (DART) Orbitrap™ mass spectrometry (OT-MS) is presented for the extraction of phosphoric acid alkyl esters (tri- (TnBP), di- (HDBP), and mono-butyl phosphate (H2MBP)) from aqueous samples. First, SBSE of phosphate esters was performed using a Twister™ coated with 24 μL of polydimethylsiloxane (PDMS) as the extracting phase. SBSE was optimized for extraction pH, phase ratio (PDMS volume/aqueous phase volume), stirring speed, extraction time and temperature. Then, coupling of SBSE to DART/Orbitrap-MS was achieved by placing the Twister™ in the middle of an open-ended glass tube between the DART and the Orbitrap™. The DART mass spectrometric response of phosphate esters was probed using commercially available and synthesized alkyl phosphate ester standards. The positive ion full scan spectra of alkyl phosphate triesters (TnBP) was characterized by the product of self-protonation [M + H]⁺ and, during collision-induced dissociation (CID), the major fragmentation ions corresponded to consecutive loss of alkyl chains. Negative ionization gave abundant [M − H]⁻ ions for both HDnBP and H2MnBP. Twisters™ coated with PDMS successfully extracted phosphate acid esters (tri-, di- and mono-esters) granted that the analytes are present in the aqueous solution in the neutral form. SBSE/DART/Orbitrap-MS results show a good linearity between the concentrations and relative peak areas for the analytes in the concentration range studied (0.1–750 ng mL⁻¹). Reproducibility of this SBSE/DART/Orbitrap-MS method was evaluated in terms of %RSD by extracting a sample of water fortified with the analytes. The %RSDs for TnBP, HDnBP and H₂MnBP were 4, 3 and 3% (n = 5) using the respective perdeuterated internal standards. Matrix effects were investigated by matrix matched calibration standards using underground water samples (UWS) and river water samples (RWS). Matrix effects were effectively compensated by the addition of the perdeuterated internal standards. The application of this new SBSE/DART/Orbitrap-MS method should be very valuable for on-site sampling/monitoring, limiting the transport of large volumes of water samples from the sampling site to the laboratory.     

Direct analysis in real time mass spectrometry (DART‐MS) of highly non‐polar low molecular weight polyisobutylenes

Low molecular weight polyisobutylenes (PIB) with chlorine, olefin and succinic acid end‐groups were studied using direct analysis in real time mass spectrometry (DART‐MS). To facilitate the adduct ion formation under DART conditions, NH₄Cl as an auxiliary reagent was deposited onto the PIB surface. It was found that chlorinated adduct ions of olefin and chlorine telechelic PIBs, i.e. [M + Cl]^? up to m/z 1100, and the deprotonated polyisobutylene succinic acid [M? H]^? were formed as observed in the negative ion mode. In the positive ion mode formation of [M + NH₄]⁺, adduct ions were detected. In the tandem mass (MS/MS) spectra of [M + Cl]^?, product ions were absent, suggesting a simple dissociation of the precursor [M + Cl]^? into a Cl^? ion and a neutral M without fragmentation of the PIB backbones. However, structurally important product ions were produced from the corresponding [M + NH₄]⁺ ions, allowing us to obtain valuable information on the arm‐length distributions of the PIBs containing aromatic initiator moiety. In addition, a model was developed to interpret the oligomer distributions and the number average molecular weights observed in DART‐MS for PIBs and other polymers of low molecular weight. Copyright © 2015 John Wiley & Sons, Ltd.     

Capillary electrophoresis chips for screening of endotoxin chemotypes from whole-cell lysates

A fast microchip electrophoresis method was developed to analyze and differentiate bacterial endotoxins directly from whole-cell lysates after removal of the proteinaceous components with proteinase K digestion and a precipitation of the endotoxin components. The partially purified endotoxin components were visualized by the interaction with dodecyl sulphate and then a fluorescent dye. The lipopolysaccharide (LPS) profiles can be directly evaluated from digested bacterial cells, and the electrophoresis patterns very closely resembled to those of pure LPSs, and the R and S chemotypes can be used to assign the strains. The method has been found to be useful in the screening of a large number of bacterial mutants and the structural characterization of endotoxins extracted only from 1 ml cultures.     

Some new features of Direct Analysis in Real Time mass spectrometry utilizing the desorption at an angle option

The present study is a first step towards the unexplored capabilities of Direct Analysis in Real Time (DART) mass spectrometry (MS) arising from the possibility of the desorption at an angle: scanning analysis of surfaces, including the coupling of thin‐layer chromatography (TLC) with DART‐MS, and a more sensitive analysis due to the preliminary concentration of analytes dissolved in large volumes of liquids on glass surfaces. In order to select the most favorable conditions for DART‐MS analysis, proper positioning of samples is important. Therefore, a simple and cheap technique for the visualization of the impact region of the DART gas stream onto a substrate was developed. A filter paper or TLC plate, previously loaded with the analyte, was immersed in a derivatization solution. On this substrate, owing to the impact of the hot DART gas, reaction of the analyte to a colored product occurred. An improved capability of detection of DART‐MS for the analysis of liquids was demonstrated by applying large volumes of model solutions of coumaphos into small glass vessels and drying these solutions prior to DART‐MS analysis under ambient conditions. This allowed the introduction of, by up to more than two orders of magnitude, increased quantities of analyte compared with the conventional DART‐MS analysis of liquids. Through this improved detectability, the capabilities of DART‐MS in trace analysis could be strengthened. Copyright © 2011 John Wiley & Sons, Ltd.     

CE to monitor endotoxins by protein complexation

A new CE method for fast and efficient analysis of bacterial endotoxins (lipopolysaccharides) is described. It is based on the strong interaction between proteins and endotoxins. The UV absorption of the protein component in the complex is used for the detection. The electrophoretic mobility of the complex hemoglobin/endotoxin can be employed for qualitative analysis of the endotoxin. For instance, the structural differences between "smooth" and "rough" lipopolysaccharides from Salmonella minnesota (wild-type), Salmonella minnesota R595 and Shigella sonnei R562H are reflected in the electrophoretic mobilities of their hemoglobin complex.     

Qualitative and quantitative analysis of polycyclic polyprenylated acylphloroglucinols from Garcinia species using ultra performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry

Polycyclic polyprenylated acylphloroglucinols (PPAPs) are a group of natural products isolated from different Garcinia species with a wide range of important biological activities. In this study, an ultra performance liquid chromatography (UPLC) coupled to photodiode-array detection and quadrupole time-of-flight mass spectrometry (Q-TOF) method was developed to characterize 16 PPAPs in 10 Garcinia species. In source dissociation techniques based on cone voltage fragmentation were used to fragment the deprotonated molecules and multiple mass spectrometry (MS/MS) using ramping collision energy were used to further break down the resulting product ions. The resulting characteristic fragment ions were generated by cleavage of C1-C5 bond and C7-C8 bond through concerted pericyclic reaction, which is especially valuable for differentiating three types of PPAPs isomers. As such, two new PPAPs isomers present in minor amount in the extracts of Garcinia oblongifolia were tentatively characterized by comparing their tandem mass spectra to the known ones. In addition, an UPLC-Q-TOF-MS method was validated for the quantitative determination of PPAPs. The method exhibited limits of detection from 2.7 to 21.4 ng mL⁻¹ and intra-day and inter-day variations were less than 3.7% and the recovery was in the range of 89-107% with RSD less than 9.0%. This UPLC-Q-TOF-MS method has successfully been applied to quantify 16 PPAPs in 32 samples of 10 Garcinia species, which were found to be a rich source of PPAPs.     

Ambient generation of fatty acid methyl ester ions from bacterial whole cells by direct analysis in real time (DART) mass spectrometry

Direct analysis in real time (DART) is implemented on a time-of-flight (TOF) mass spectrometer, and used for the generation of fatty acid methyl esters (FAMEs) ions from whole bacterial cells.     

Characterization and identification of steroidal alkaloids in Fritillaria species using liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry

Liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (LC/ESI-QTOF-MS/MS) was performed to study the fragmentation behaviors of steroidal alkaloids from Fritillaria species, the antitussive and expectorant herbs widely used in traditional Chinese medicine. We propose, herein, a strategy that combining key diagnostic fragment ions and the relative abundances and amounts of major fragment ions (the ions exceeding 10% in abundance) to distinguish different sub-classes of Fritillaria alkaloids (FAs). It was found that hydrogen rearrangement and induction effects result in ring cleavage of the basic skeletons occurred in the MS/MS process and produced characteristic fragment ions, which are useful for structural elucidation. This method was finally used to investigate the primary steroidal alkaloids in the extracts of eight major Fritillaria species. As a result, 41 steroidal alkaloids (29 cevanine type, 1 jervine type, 6 veratramine type and 5 secosolanidine type alkaloids) were selectively identified in these Fritillaria species. Twenty-six compounds were unambiguously identified by comparing with the reference compounds and 15 compounds were tentatively identified or deduced according to their MS/MS data. Logical fragmentation pathways for different types of FAs have been proposed and are useful for the identification of these types of steroidal alkaloids in natural products especially when there are no reference compounds available.     

Silver(I) complexes based on novel tripodal thioglycosides: synthesis, structure and antimicrobial activity

The reaction of tris(2-bromoethyl)amine hydrobromide with sugar thiols or thioacetates leads to the formation of novel carbohydrate substituted tripodal NS₃ ligands. Complexation with silver(I) ions gives stable complexes. NMR, X-ray, MS and EXAFS studies indicate their mononuclear C₃-symmetric structure. The highly water soluble complexes formed from the unprotected ligands show a wide spectrum of effective antimicrobial activities and their use lowers the cytotoxic and antiproliferative activities compared to the free silver salts.     

The unanticipated loss of SO2 from sulfonamides in collision-induced dissociation

A potent and selective sulfonamide beta3 agonist with an excellent pharmacokinetic profile has recently been synthesized. During the analysis by liquid chromatography/tandem mass spectrometry (LC/MS/MS) of metabolites of the sulfonamide N-[4-[2-(2-hydroxy-2-pyridin-3-ylethylamino)ethyl]phenyl]-4-[4-(4-trifluoromethylphenyl)thiazol-2-yl]benzulfonamide (compound A), we observed loss of 64 Da for a few of the metabolites in the negative ion mode. Accurate mass measurements performed with Fourier transform ion cyclotron resonance (FTICR) mass spectrometry and quadrupole time-of-flight (Q-TOF) mass spectrometry suggested that the loss of 64 Da corresponded to the loss of SO(2). The same phenomenon was observed for a group of structurally related and commercially available compounds that also contain a sulfonamide moiety. MS/MS analysis of the fragment ions that had lost SO(2) in the ion source suggested that these ions were covalently bound rather than ion-molecule complexes. The neutral loss involving the cleavage of two bonds was unanticipated and suggested a complex rearrangement process. A mechanism for the loss of SO(2) has been proposed.     

Rapid qualitative analysis of 2 flavonoids,rutin and silybin,in medical pills by direct analysis in real‐time mass spectrometry (DART‐MS) combined with in situ derivatization

Direct analysis in real‐time mass spectrometry (DART‐MS) with in situ silylation was used for the rapid analysis of the flavonoids silybin ((2R,3R)‐3,5,7‐trihydroxy‐2‐[3‐(4‐hydroxy‐3‐methoxyphenyl)‐2‐hydroxymethyl‐2,3‐dihydrobenzo[1,4]dioxin‐6‐yl]chroman‐4‐one) and rutin (quercetin‐3‐O‐rutinoside). Three different derivatization reagents, hexamethyldisilazane/trimethylchlorosilane/pyridine (HMDS/TMCS/pyridine), N,O‐bis(trimethylsilyl)acetamide/trimethylchlorosilane/N‐trimethylsilyimidazole (BSA/TMCS/TMSI), and N,O‐bis(trimethylsilyl)trifluoroacetamide/trimethylchlorosilane (BSTFA/TMCS), were applied. Silybin and rutin were detected with various degrees of silylation, and the formation of dimers with pyridine and imidazole was also observed. HMDS/TMCS/pyridine was the best choice for the DART‐MS analysis of silybin, and BSA/TMCS/TMSI was the most effective for the detection of rutin. The effects of the DART source temperature on desorption, ionization, in‐source fragmentation, dimer formation, and hydrolysis of the trimethylsilyl groups were also studied. In addition, the collision‐induced dissociation properties of the derivatized silybin and rutin were explored. With our in situ silylation method, the derivatized bioactive compounds in intact medical pills could also be detected by DART‐MS.     

Characterization of braun’s lipoprotein and determination of its attachment sites to peptidoglycan by 252Cf-PD and MALDI time-of-flight mass spectrometry

A strategy for the characterization of bacterial lipoprotein-in this case Braun’s lipoprotein (an outer membrane 7-ku lipoprotein) isolated from Escherichia coli—is described by time-of-flight mass spectrometric (TOF/MS) techniques [²⁵²Cf plasma desorption (PD) TOF/MS and matrix-assisted laser desorption-ionization (MALDI) TOF/MS]. Covalent linkage of lipid at the N-terminal cysteine (posttranslationally modified to a S-[2,3-bis(acyloxy)-propyl]-N-acylcysteine) and, therefore, strict insolubility in aqueous solution constitute common features for this class of proteins. Relative molecular mass determination of the major molecular species of Braun’s lipoprotein was obtained by selection of an appropriate mixture of organic solvents compatible with matrix/support materials useful for the mass spectrometric techniques applied. Minor components of this lipoprotein that differ only in the fatty acid composition of the lipid anchor were detected by PD TOF/MS after enzymatic release of the extremely hydrophobic N-terminal amino acid followed by selective extraction with chloroform. Part of the primary sequence of this lipoprotein was confirmed based on peptide fragment ions observed in the positive ion PD mass spectra of cyanogen bromide-generated peptide fragments that had been isolated previously by reverse phase high-performance liquid chromatography (HPLC). Peptidoglycan fragments that represent the attachment sites of lipoprotein to peptidoglycan were enzymatically released, separated by reverse phase HPLC, and finally characterized by time-of-flight mass spectrometric techniques (²⁵²Cf-PD TOF/MS, MALDI TOF/MS). The results obtained with both techniques differed only in the better sensitivity obtained with MALDI TOF/MS, which consumed a factor of 100 to 1000 less material than with PD TOF/MS.     

Detection of polydimethylsiloxanes transferred from silicone‐coated parchment paper to baked goods using direct analysis in real time mass spectrometry

The non‐stick properties of parchment papers are achieved by polydimethylsiloxane (PDMS) coatings. During baking, PDMS can thus be extracted from the silicone‐coated parchment into the baked goods. Positive‐ion direct analysis in real time (DART) mass spectrometry (MS) is highly efficient for the analysis of PDMS. A DART‐SVP source was coupled to a quadrupole‐time‐of‐flight mass spectrometer to detect PDMS on the contact surface of baked goods after use of silicone‐coated parchment papers. DART spectra from the bottom surface of baked cookies and pizzas exhibited signals because of PDMS ions of the general formula [(C₂H₆SiO)_n + NH₄]⁺ in the m/z 800–1900 range. Copyright © 2016 John Wiley & Sons, Ltd.     

Diagnostic filtering to screen polycyclic polyprenylated acylphloroglucinols from Garcinia oblongifolia by ultrahigh performance liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry

A novel multistage MS approach, insource collision-induced dissociation (CID) combined with Time Aligned Parallel (TAP) fragmentation, was established to study the fragmentation behavior of polycyclic polyprenylated acylphloroglucinols (PPAPs), which could provide a more reliable fragmentation relationship between precursor and daughter ions. The diagnostic ions for different subtypes of PPAPs and their fragmentation behaviors have been summarized. Moreover, a new and reliable multidimensional analytical workflow that combines ultrahigh performance liquid chromatography (UHPLC), data-independent mass spectrometry (MS^E), and tandem MS with ion mobility (IM) has been optimized and established for the analysis of PPAPs in the plant Garcinia oblongifolia by diagnostic filtering. Diagnostic fragment ions were used to selectively screen PPAPs from extracts, whereas IM coupled to MS was used to maximize the peak capacity. Under the optimized UHPLC-IM-MS^E and UHPLC-IM-MS/MS method, 140 PPAPs were detected from the crude extract of G. oblongifolia, and 10 of them were unambiguously identified by comparing them to the reference compounds. Among those PPAPs, 7 pairs of coeluting isobaric PPAPs that were indistinguishable by conventional UHPLC-HRMS alone, were further resolved using UHPLC-IM-MS. It is anticipated that the proposed method will be extended to the rapid screening and characterization of the other targeted or untargeted compounds, especially these coeluting isomers in complex samples.