ABSTRACT
Three kinds of glass sharp electrospray ionization devices were built for direct mass spectrometry (MS) analysis using sharp slide,slender capillary and sharp dropper. Through the simulation experiment and mass spectrometry experimental investigation,the influence of the experimental conditions was studied. Under the optimum working conditions such as the electrospray tip diameter was less than 0.24 mm, the distance between the electrospray tip and the MS sample inlet was 10 mm, the electrospray voltage was 4.5 kV, the electrospray capillary angle was about 5.0°-7.5° (upper at back) and the left and right angles were 0°, 0.1 mg/mL sample solution(containing 1% formic acid for positive ion detection,or ammonium hydroxide for negative ion detection) could be well analyzed by MS. In positive or negative ion modes, the quinine, mandelic acid,benzoin,phenylalanine and other different types of sample solutions were analyzed by MS. The result showed that quinine,mandelic acid,benzoin,phenylalanine,tartaric acid,2,5-dihydroxybenzoic acid (DHB) and tangeretin could be detected in positive ion mode using sharp dropper electrospray. DHB, phenylalanine, tartaric acid and mandelic acid were detected in negative ion mode. Sharp slide electrospray was suitable for measuring the stable sample in the air, capillary electrospray and sharp dropper electrospray were suitable for detecting many low viscosity sample solution even instable sample. Using the method, the extraction solution of propranolol hydrochloride tablet and berberine hydrochloride tablet was directly analyzed by MS. The results showed that the glass sharp electrospray method had the advantages such as without carrier gas, simple structure, easy to build and operate, rapid analysis, anti-cross pollution, and could be conveniently used for MS analysis.
ABSTRACT
The ionic liquid butylamine 2,5-dihydroxybenzoate (DHB-BuN) was chosen as the matrix for improving repeatability of oligosaccharides quantitation, and imaging oligosaccharides in soybean and leaf by matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS).Using the ionic liquid matrix methanol solution (20%, V/V) to cover sample slice, and setting MS acquisition parameters including polarity as positive and laser power as 70%, the MS imaging experiment was performed to analyze oligosaccharides and their distribution in soyben and soybean leaf.As a result, the MALDI-MS analysis of 3 kinds of oligosaccharides including sucrose, raffinose and stachyose was performed using the ionic liquid matrix and the reproducibility RSDs were less than 3% for in-spot and less than 4% for spot-to-spot.The standard curves linear correlation coefficients (R2) were all no less than 0.996 between MS peak intensity and oligosaccharides concentraions in the concentration rage of 0.062-1.00 mg/mL, which showed quantitative power in MALDI-MS analysis.The matrix was used for MALDI-MS imaging analysis of soybean chips and soybean leaf surface disaccharide, trisaccharide and tetrasaccharide to obtain the soybean mass spectrum and spatial resolution of 150 μm of the three oligosaccharides imaging.Three kinds of oligosaccharides in the soybean roughly balanced distribution, and the oligosaccharides distribution in the leave was mostly at its tip part.The contents of the 3 kinds of oligosaccharides could be estimated by their MS peak intensity and above standard curve.The result suggested that the ionic liquid DHB-BuN matrix could be well applied in MALDI-MS imaging analysis of oligosaccharides in different sample.
ABSTRACT
A novel ionization enhancer, methylamine formate, was proposed for improving the detection sensitivity of triglyceride in edible oil by reversed phase liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS).The commonly used isopropanol-acetonitrile-methanol-water and isopropanol-acetonitrile were selected as the mobile phase.By using a reversed phase C18 column, and taking the corn oil in isopropyl alcohol as sample solution, we compared methylamine formate with ammonium formate, as ionization enhancers, for their effect on the detection sensitivity of triglyceride by LC-ESI-MS after screening other different ionization enhancers, such as formic acid, acetic acid, ammonium formate, ammonium acetate, butyl formate, dibutylamine formate, triethylamine formate, diethylamine formate, methylamine formate, and ethylamine formate.The result indicated that, by using methylamine formate, the mass spectral peak response and the signal to noise ratio for trilinoleic glyceride component were 5 times higher than that of ammonium formate.The effect of the concentration of methylamine formate ionization enhancer, the flow rate of the mobile phase and the flow rate of nebulizing gas on the detection of methylamine formate were investigated.The concentration of triglyceride components in corn oil starting to form aggregates was similar in different mobile phases in the electrospray process according to measurement of the relationship between corn oil concentrations and the total ion chromatogram peak area of triglyceride.In particular, the peak area of trilinolein was linear with its concentration in the range of 7×10-7-2×10-4 mol/L (R2=0.9997), but increased slower in the higher concentration range.According to the experimental data, the mechanism for improvement of detection sensitivity of methylamine formate was suggested as that the addition of methylamine mono-charged ions with hydrophobic groups had lower solvation energy, which made the enriched addition ions easily evaporation from the droplet surface, thus improving the electrospray ionization efficiency.This method provided an effective way to improve the detection sensitivity of triglyceride in edible oil by LC-ESI-MS.
ABSTRACT
The method of quantitative nuclear magnetic resonance spectroscopy (qNMR) for determination of epigoitrin in Radix Isatidis was established based on solid phase extraction (SPE).The twice ultrasonic extraction method using pure water was used for fully extracting epigoitrin in sample, and then the extraction was enriched and concentrated by poly-Sery MCX SPE cartridge.The effect of sample pretreatment and qNMR experimental conditions was investigated.The qNMR experiment conditions were selected using DMSO as solvent, calibrated 2,3,5-triiodobenzoate as internal standard, and P1(pulse width)=14.1 μs, d1(pulse delay time)=5 s, NS(number of scan)=256.The .1H-NMR peaks of δ 5.365-5.399 (H-7b, d, 1H) of epigoitrin were chosen as the quantitative peaks.Method validation was performed including precision (intra-day precision RSD was 0.5%, and the inter-day precision was 0.8%), linearity (correlation coefficient r>0.9991), LOD (0.05 mg/g, standard curve method) and LOQ (0.19 mg/g, S/N≥150).The recoveries of the SPE-qNMR were 97.4%-101.7%.The result showed that the method was stable, accurate and reliable.With this method the epigoitrin in a real Radix Isatidis was determined to be <0.19-1.26 mg/g.SPE combining with qNMR could extend the application field of qNMR, especially in the detection of low-content component in complex samples.
ABSTRACT
An atmospheric pressure chemical ionization mass spectrometry (APCI-MS) method was developed for the direct analysis of triglycerides in edible oils.The edible oil sample was dissolved in acetonitrile.Under the optimal conditions such as positive ion detection,800 μL/h of sample flow rate,250℃ of vaporizer temperature and 5000 nA of corona needle current,the repeatability (RSD) of peak intensity rate of m/z 857.76 to m/z 881.76 was less than 5％.Then,different kinds of oil from different manufacturers were analyzed by the proposed method.After a principal component analysis for the analytical results,the peak intensity rate of m/z 857.76 and m/z 881.76 was selected for oil identification.The adulteration of 5％ lard in corn oil could be recognized directly using the peak intensity rate.Three characteristic triglycerides in edible oil were preliminarily identified by collision induced dissociation (CID) experiments.The method was applied to analyze the swill oil and fried oil samples,and the results showed that the swill oil contained both vegetable oil and animal fat,and the fried oil was also different with commercial vegetable oil.
ABSTRACT
Objective To present the changing of the parameters of orbital volume after endoscopic transethmoid medial orbital wall decompression combined with the endoscopic transethmoid intraconal fat-removal orbital decompression in thyroid associated ophthalmopathy (TAO).Methods A retrospective chart was reviewed in 11 patients (20 eyes) receiving orbital decompression for the treatment of exophthalmos secondary to TAO from September 2014 to August 2015. All patients diagnosed TAO were in stable and inactive phase at least for 6 months. High-resolution computed tomography (HRCT) scan were performed in all patients before and 3-month after surgery. CT scan of orbit and computer-aided measurement software were used to measure the exophthalmos. Changing of the parameters of orbital volume were recorded for analysis its relationship with the amount of proptosis reduction.Results The exophthalmos was signiifcantly decreased after surgery. Medial rectus volume, fat volume and orbital volume were larger postoperatively. The changing of rectus volume and fat volume both had negative correlationship with the amount of proptosis.Conclusions The thickening of medial rectus 3-month postoperative may due to the removing of medial wall of orbit during the surgery. The stimulation of the surgery may be another reason. The changing of rectus volume and fat volume both had negative correlationship with the amount of proptosis.
ABSTRACT
Cisplatin is effective in the treatment of various solid tumors. However, its clinical application is limited because of the severe side-effects such as nephrotoxicity, hepatotoxicity, ototoxicity and so on. Drug combination is advocated in clinics for synergism and detoxication. In order to provide some referencs for the research of drug combination and clinical treatment regimen, the research advances in the synergism and detoxication of drug combination of cisplatin with chemicals/ traditional Chinese medicines in recent years are reviewed in the paper.