Electrospun fibrous thin film microextraction coupled with desorption corona beam ionization-mass spectrometry for rapid analysis of antidepressants in human plasma.

Appropriate sample preparations prior to analysis can significantly enhance the sensitivity of ambient ionization techniques, especially during the enrichment or purification of analytes in the presence of complex biological matrix. Here in, we developed a rapid analysis method by the combination of thin film microextraction (TFME) and desorption corona beam ionization (DCBI) for the determination of antidepressants in human plasma. Thin films used for extraction consisted of sub-micron sized highly ordered mesoporous silica-carbon composite fibers (OMSCFs), simply prepared by electrospinning and subsequent carbonization.

Magnetic solid phase extraction coupled with desorption corona beam ionization-mass spectrometry for rapid analysis of antidepressants in human body fluids.

Ambient ionization techniques show good potential in rapid analysis of target compounds. However, a direct application of these ambient ionization techniques for the determination of analytes in a complex matrix is difficult due to the matrix interference and ion suppression. To resolve this problem, here we developed a strategy by coupling magnetic solid phase extraction (MSPE) with desorption corona beam ionization (DCBI)-mass spectrometry (MS).

Metal Oxide-Based Selective Enrichment Combined with Stable Isotope Labeling-Mass Spectrometry Analysis for Profiling of Ribose Conjugates.

Some modified ribonucleosides in biological fluids have been evaluated as cancer-related metabolites. Detection of endogenous modified ribonucleosides in biological fluids may serve as a noninvasive cancers diagnostic method. However, determination of modified ribonucleosides is still challenging because of their low abundance and serious matrix interferences in biological fluids.

Coupling carbon nanotube film microextraction with desorption corona beam ionization for rapid analysis of Sudan dyes (I-IV) and Rhodamine B in chilli oil.

A rapid analysis method by coupling carbon nanotube film (CNTF) microextraction with desorption corona beam ionization (DCBI) was developed for the determination of Sudan dyes (I-IV) and Rhodamine B in chilli oil samples. Typically, CNTF was immersed into the diluted solution of chilli oil for extraction, which was then placed directly under the visible plasma beam tip of the DCBI source for desorption and ionization. Under optimized conditions, five dyes were simultaneously determined using this method.

Profiling of thiol-containing compounds by stable isotope labeling double precursor ion scan mass spectrometry.

Here we developed a novel strategy of isotope labeling in combination with high-performance liquid chromatography-double precursor ion scan mass spectrometry (IL-LC-DPIS-MS) analysis for nontargeted profiling of thiol-containing compounds. In this strategy, we synthesized a pair of isotope labeling reagents (ω-bromoacetonylquinolinium bromide, BQB; ω-bromoacetonylquinolinium-d7 bromide, BQB-d7) that contain a reactive group, an isotopically labeled moiety, and an ionizable group to selectively label thiol-containing compounds. The BQB and BQB-d7 labeled compounds can generate two characteristic product ions m/z 218 and 225, which contain an isotope tag and therefore were used for double precursor ion scans in mass spectrometry analysis.

Isotope labelling--paired homologous double neutral loss scan-mass spectrometry for profiling of metabolites with a carboxyl group.

We developed a novel method for non-targeted screening of metabolites by high performance liquid chromatography-mass spectrometry with paired homologous double neutral loss scan mode after in vitro isotope labelling (IL-HPLC-PHDNL-MS). As a proof of concept, we investigated the carboxylic acid metabolite profiling in plant samples by the IL-HPLC-PHDNL-MS method. To this end, N,N-dimethylaminobutylamine (DMBA) and d(4)-N,N-dimethylaminobutylamine (d(4)-DMBA) were synthesized and utilized to label carboxylic acids.

Quick, easy, cheap, effective, rugged and safe method with magnetic graphitized carbon black and primary secondary amine as adsorbent and its application in pesticide residue analysis.

By using magnetic graphitized carbon black and primary secondary amine (GCB/PSA/MNPs) as adsorbent, a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method was proposed for pesticide residue analysis in vegetables. The magnetic adsorbent was fabricated via simple co-mixing method based on an "aggregate warp" mechanism. To achieve the optimum conditions of modified QuEChERS toward target analytes, several parameters, including the composition of analyte protectants and the amount of the adsorbents were investigated.

Spectroscopic observation of iodosylarene metalloporphyrin adducts and manganese(V)-oxo porphyrin species in a cytochrome P450 analogue.

Different metalloporphyrin model compounds have been synthesized to study the mechanisms of cytochrome P450s with various terminal oxidants, and numerous intermediates have been reported. However, the detailed mechanism of the oxygen atom transfer from iodosylarene to the substrates remains unclear. Here we report the direct ultraviolet-visible spectroscopic observation of the soluble iodosylarene-manganese porphyrin adduct following catalytic oxidation using 2,4,6-tri-tert-butylphenol as the reductant.

Alterations of mitochondrial protein assembly and jasmonic acid biosynthesis pathway in Honglian (HL)-type cytoplasmic male sterility rice.

It has been suggested that the mitochondrial chimeric gene orfH79 is the cause for abortion of microspores in Honglian cytoplasmic male sterile rice, yet little is known regarding its mechanism of action. In this study, we used a mass spectrometry-based quantitative proteomics strategy to compare the mitochondrial proteome between the sterile line Yuetai A and its fertile near-isogenic line Yuetai B. We discovered a reduced quantity of specific proteins in mitochondrial complexes in Yuetai A compared with Yuetai B, indicating a defect in mitochondrial complex assembly in the sterile line.

Highly sensitive and quantitative profiling of acidic phytohormones using derivatization approach coupled with nano-LC-ESI-Q-TOF-MS analysis.

In current study, we developed a highly sensitive method for the quantitative profiling of acidic phytohormones. Tandem solid-phase extraction (SPE) and liquid-liquid extraction (LLE) was employed to efficiently purify acidic phytohormones, which were further derived by 3-bromoactonyltrimethylammonium bromide (BTA) to increase the ionization efficiency in electrospray ionization-mass spectrometry detection. Additionally, fifteen BTA-derived acidic phytohormones, including ten gibberellins (GAs), were well separated with a salt gradient on poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MAA-co-EDMA) monolithic column.

Sample preparation and direct electrospray ionization on a tip column for rapid mass spectrometry analysis of complex samples.

A handheld pipette tip column electrospray ionization source (PTC-ESI source) was developed for rapid mass spectrometry analysis at ambient pressure. The PTC-ESI source was made up of three main component parts including a micro DC high voltage (HV) power supply, a micropipette and a disposable micropipette tip filled with a plug of adsorbent. A DC high voltage was applied to the sharp point of the micropipette tip column to induce electrospray ionization.

Coupling frontal elution paper chromatography with desorption corona beam ionization mass spectrometry for rapid analysis of chlorphenamine in herbal medicines and dietary supplements.

We developed a convenient method by coupling frontal elution paper chromatography with desorption corona beam ionization mass spectrometry (DCBI-MS) for rapid determination of chlorphenamine added in herbal medicines or dietary supplements. In this method, the ethanol extract of the herbal products was spotted directly onto an isosceles triangular filter paper sheet, and then the paper sheet was developed under strong elution condition with the sample zone migrating at the solvent front. The analyte was finally condensed at the V-shaped tip which could then be placed under the visible plasma beam of DCBI for ionization.

Use of isotope differential derivatization for simultaneous determination of thiols and oxidized thiols by liquid chromatography tandem mass spectrometry.

Here we report a new isotopic pair of derivatization reagents, ω-bromoacetonylquinolinium bromide (BQB) and d(7)-ω-bromoacetonylquinolinium bromide (d(7)-BQB). BQB and d(7)-BQB both rapidly and selectively reacted with thiols in acidic medium within 3min with the aid of a microwave. Reduced thiols and total thiols in urine were labeled with BQB and d(7)-BQB, respectively.

Highly sensitive profiling assay of acidic plant hormones using a novel mass probe by capillary electrophoresis-time of flight-mass spectrometry.

Plant hormones play crucial roles in plant growth and development. However, up to date, identification and quantification of acidic plant hormones with trace amount in complicated plant matrix is still a challenge. In current study, we developed a high sensitive assay for the determination of acidic plant hormones in rice by combining capillary electrophoresis and electrospray ionization-time of flight-mass spectrometry (CE-ESI-TOF-MS).

Use of isotope mass probes for metabolic analysis of the jasmonate biosynthetic pathway.

In order to quantitatively study the jasmonate biosynthetic pathway, we chemically synthesized a pair of isotope mass probes and established a labeling protocol. The pair of mass probes used in our work were ω-bromoacetonylpyridinium bromide (BPB) and d(5)-ω-bromoacetonylpyridinium bromide (d(5)-BPB), which contain carboxylic acid reactive groups, isotopically labeled groups and permanent positive charges. High performance liquid chromatography (HPLC) and electrospray ionization quadrupole-time of flight mass spectrometry (ESI-QTOF-MS) were used for the detection of labeled standard mixtures and plant samples.