Quadruple Time Of Flight Mass Spectrometry Research Articles

Molecular characteristics and antioxidant activity of laminarin extracted from the seaweed species Laminaria hyperborea, using hydrothermal-assisted extraction and a multi-step purification procedure

The objective of this study was to determine the effect of hydrothermal-assisted extraction (HAE) and a multi-step purification process on the molecular characteristics and antioxidant activity of extracts of laminarin from the brown seaweed Laminaria hyperborea. The HAE with optimised extraction conditions (time - 30 min; temperature - 99.3 °C; sample to solvent ratio - 1:21.3 (w/v)) resulted in 368 mg/g laminarin in the Crude Extract. Purification using solvents, molecular weight cut-off filter (MWCO; 10 kDa) and solid-phase extraction (SPE) improved the concentration to 542.6 mg/g, 906.6 mg/g and 862.5 mg/g on dry weight extract basis, respectively (p < 0.05). The crude HAE extract had greater antioxidant activity, as determined by 1,1-diphenyl-2-picryl-hydrazyl radical scavenging and ferric reducing antioxidant power assays, than the purified fractions (p > 0.05). The identification of a chromatographic peak at 17.66 min (retention time) and FT-IR (Fourier transform infrared) absorption bands at 1420 cm−1 (carboxyl groups), 2950 cm−1 (C-H stretch) and at 2410 cm−1 (transmitting angle peak) was similar between the purified samples and a laminarin standard that was used as a control, confirming the presence of laminarin. The quadruple time of flight mass spectrometry (Q-ToF-MS) confirmed the molecular weight of purified laminarin was in the range of 5.7 kDa–6.2 kDa. HAE under optimised conditions was an effective method to recover biologically active laminarin from L. hyperborea. A multi-step purification, involving solvents and MWCO filters in a sequence could improve the purity of laminarin, however, purification reduced the antioxidant activity compared to the crude HAE extract.

Screening for abnormal glycosylation in a cohort of adult liver disease patients.

Congenital disorders of glycosylation (CDG) are a rapidly expanding group of rare genetic defects in glycosylation. In a novel CDG subgroup of vacuolar‐ATPase (V‐ATPase) assembly defects, various degrees of hepatic injury have been described, including end‐stage liver disease. However, the CDG diagnostic workflow can be complex as liver disease per se may be associated with abnormal glycosylation. Therefore, we collected serum samples of patients with a wide range of liver pathology to study the performance and yield of two CDG screening methods. Our aim was to identify glycosylation patterns that could help to differentiate between primary and secondary glycosylation defects in liver disease. To this end, we analyzed serum samples of 1042 adult liver disease patients. This cohort consisted of 567 liver transplant candidates and 475 chronic liver disease patients. Our workflow consisted of screening for abnormal glycosylation by transferrin isoelectric focusing (tIEF), followed by in‐depth analysis of the abnormal samples with quadruple time‐of‐flight mass spectrometry (QTOF‐MS). Screening with tIEF resulted in identification of 247 (26%) abnormal samples. QTOF‐MS analysis of 110 of those did not reveal glycosylation abnormalities comparable with those seen in V‐ATPase assembly factor defects. However, two patients presented with isolated sialylation deficiency. Fucosylation was significantly increased in liver transplant candidates compared to healthy controls and patients with chronic liver disease. In conclusion, a significant percentage of patients with liver disease presented with abnormal CDG screening results. However, the glycosylation pattern was not indicative for a V‐ATPase assembly factor defect. Advanced glycoanalytical techniques assist in the dissection of secondary and primary glycosylation defects.

Purification, Identification, and Sensory Evaluation of Kokumi Peptides from Agaricus bisporus Mushroom.

Agaricus bisporus can enhance the umami and salty taste in chicken soup, and also has a high protein content, which indicates that there might be some kokumi taste compounds in this mushroom. Therefore, through ultrafiltration, gel permeation chromatography (GPC), and reverse phase-high performance liquid chromatography (RP-HPLC), some peptides in fresh Agaricus bisporus mushroom were isolated. Then, these peptides were identified by sensory evaluation and ultra performance liquid chromatography (UPLC) coupled quadruple time of flight mass spectrometry (Q-TOF-MS). The sensory evaluation results showed that the addition of aqueous extract isolated from Agaricus bisporus to model chicken broth did enhance chicken broth’s complexity, mouthfulness, and palatability. UPLC-Q-TOF-MS analysis found that Gly-Leu-Pro-Asp (Mw = 399.99) and Gly-His-Gly-Asp (Mw = 383.99) might act as key molecules to cause kokumi taste. In order to verify the kokumi taste of the above two peptides, they were synthesized by solid-phase synthesis and the taste properties of these two peptides were further characterized by descriptive sensory evaluation and taste intensity tests. This work indicated that it was feasible to produce kokumi peptides from Agaricus bisporus.

Metabolite characterization of ambrisentan, in in vitro and in vivo matrices by UHPLC/QTOF/MS/MS: Detection of glutathione conjugate of epoxide metabolite evidenced by in vitro GSH trapping assay

The focus of the present study is on in vitro and in vivo metabolite identification of ambrisentan (AMBR) a selective endothelin type – A (ETA) receptor antagonist using quadruple time-of-flight mass spectrometry (QTOF/MS). in vitro metabolism study was conducted by incubating AMBR in rat liver microsomes (RLM), rat and human liver S9 fractions. In vivo study was carried out through the collection of urine, faeces and plasma samples at various time points after oral administration of AMBR in suspension form at a dose of 25 mg/kg to six male Sprague – Dawley (SD) rats. The samples were prepared using an optimized sample preparation techniques involving protein precipitation (PP), freeze liquid extraction (FLE) and solid phase extraction (SPE). The extracted samples were further concentrated and analyzed by developing a sensitive and specific liquid chromatography-mass spectrometry (LC–MS) method. A total of seventeen metabolites were identified in in vivo samples which includes hydroxyl, demethylated, demethoxylated, hydrolytic, decarboxylated, epoxide and glucuronide metabolites. Most of the metabolites were observed in faeces and urine matrices and few were observed in the plasma matrix. Only ten metabolites were identified in in vitro study which was commonly observed in in vivo study. The detailed structural elucidation of all the metabolites was done using UHPLC/QTOF/MS/MS in combination with accurate mass measurements. The toxicity profile of AMBR and its metabolites were predicted using TOPKAT software. In addition, a mass spectrometric method was developed for the detection and characterization of GSH-trapped reactive epoxide metabolitein human liver S9 fraction supplemented with glutathione (GSH) as trapping agent.

Development and validation of Q-TOF/MS method for the rapid and simultaneous quantification of three aconitum alkaloids in food

In this study, the presence of three aconitum alkaloids (aconitine, mesaconitine, and hypaconitine) in food was determined by liquid chromatography-tandem mass spectroscopy (LC-MS/MS) and quadruple time of flight mass spectrometry (Q-TOF/MS).

Identification and quantification of flavonoids and chromes in Baeckea frutescens by using HPLC coupled with diode-array detection and quadruple time-of-flight mass spectrometry

This article marks the first report on high-performance liquid chromatography (HPLC) coupled with diode-array detection (DAD) and quadruple time-of-flight mass spectrometry (Q-TOF/MS) for the identification and quantification of main bioactive constituents in Baeckea frutescens. In total, 24 compounds were identified or tentatively characterised based on their retention behaviours, UV profiles and MS fragment information. Furthermore, a validated method with good linearity, sensitivity, precision, stability, repeatability and accuracy was successfully applied for simultaneous determination of five flavonoids and one chromone in different plant parts of B. frutescens collected at different harvest times, and their dynamic contents revealed the appropriate harvest times. The established HPLC-DAD-Q-TOF/MS using multi-bioactive markers was proved to be a validated strategy for the quality evaluation on both raw materials and related products of B. frutescens.

Identification and Quantification of Aldose Reductase Inhibitory Flavonoids in Herbal Formulation and Extract of Gymnema sylvestre Using HPLC-PDA and LC-MS/MS

Adulteration of herbal supplements is a major issue for many countries. A simple and reliable HPLC-PDA method was developed for quantification of aldose reductase inhibitory flavonoids rutin, quercetin, and kaempferol. The chromatographic separation was performed on a Fortis C18 column in gradient mode with detection at 267 nm. The presence of these markers was confirmed through the accurate m/z values and MS/MS data obtained using quadruple time of flight mass spectrometry (QTOF-MS). The proposed method was successfully applied to examine the amount of these active constituents in antiobese polyherbal formulation and plant extract of Gymnema sylvestre.

Identification and differentiation of the red ink entries of seals on document by laser desorption ionization mass spectrometry

The establishment of approaches for the differentiation of the ink entries of seals on paper can provide evidence to authenticate the related documents and can play a key role in judicial expertise. The identification and discrimination method for 38 red ink entries of seals on paper has been investigated using laser desorption ionization mass spectrometry (LDI-MS). Six dye components for the ink pastes of seals, Scarlet powder (SP), Bronze Red C (BR), Fast Red R (FR), Basic Violet 3 (BV3), Pigment Red 22 (PR22) and Pigment Red 112 (PR112), have been identified by their LDI-MS spectra, and the results have been confirmed by electrospray ionization quadruple-time of flight mass spectrometry (QTOF-ESI-MS/MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The 38 ink entries were classified into six groups based on the presence or the absence of the pigments in their positive and negative LDI-MS spectra, and the discrimination power (DP) was calculated to be about 82%. The ink entries within each group were further differentiated from the relative peak areas (RPA) of the fragments for the pigments and the profile of their LDI-MS spectra, and thus the DP was increased to 98%. All the 38 ink entries could be discriminated (the DP was 100%), if including the contribution of unknown peaks. Compared with the results obtained by the FTIR and Raman methods, the established LDI-MS approach could provide more information of the dye components in the ink entries. The results showed that the developed LDI-MS method is powerful, sensitive and rapid and can directly differentiate the red ink entries of seals from paper substrates, thus offering a novel approach to judge the authenticity of documents.

Differentiation and dating of gel pen ink entries on paper by laser desorption ionization- and quadruple-time of flight mass spectrometry

The approaches for differentiation and dating of gel pen ink entries have been investigated by laser desorption ionization-time of flight mass spectrometry (LDI-TOF-MS) and high performance liquid chromatography-quadruple-time of flight mass spectrometry (HPLC-Q-TOF-MS). 45 kinds of black and blue gel pen ink entries were differentiated individually by the profiles of their LDI-MS spectra. The dye components in the black and blue ink entries have been identified by thin layer chromatography and HPLC-Q-TOF-MS methods. The degradation processes of the dye components in the ink entries under various aging conditions have been probed by LDI-MS approach. The results showed that the variations of relative intensities for the main dye components have a close relationship with aging time, and the degradation of the main dye components were significant under natural storage conditions, which can provide important evidences for dating of the ink entries on paper.

Determination of cyanidin-3-glucoside (red kernel food colour) in beverages by high performance liquid chromatography and a study of its degradation by quadruple time-of-flight mass spectrometry

A method for the determination of cyanidin-3-glucoside (red kernel colour, RKC) in various matrices, including carbonated soft drinks, fruit-based soft drinks, sugar confectionery and milk-based drinks, by high performance liquid chromatography (HPLC) based on UV–Vis detection (at 520 nm) have been developed. Pre-treatment procedures for various matrices have been optimised. For soft drinks, the pH values were adjusted to 2.0, and sugar confectionery and milk-based drinks were extracted with 30 and 50% methanol in 0.1% formic acid (pH ∼ 2.5) aqueous solutions, respectively. The limits of detection for the established methods ranged from 0.2 mg/kg for soft drinks to 2.0 mg/kg for the sugar confectionery and milk-based drinks with the relative standard deviations lower than 7%, which satisfy the method performance requirements for quality control for the beverages. The stability of the colourant RKC under various thermal and pH conditions was investigated by quadruple time-of-flight mass spectrometry (Q-TOF-MS). The main colourant component of RKC, cyanidin-3-glucoside (Cyd-3-Glu), lost the glucose entity under thermal treatment. A new component was identified when RKC degraded under various pH conditions and a degradation pathway is proposed. The results will assist in understanding the degradation mechanism of the colourant Cyd-3-Glu.