Separation and purification of deoxynivalenol(DON) mycotoxin from wheat culture using a simple two-step silica gel column chromatography

Deoxynivalenol（DON） is a type B trichothecenes mycotoxin produced by several Fusarium species, often found in foodstuffs for humans and animals. DON is in great demand for the toxicological researches both in vivo and in vitro. In this work, wheat culture was inoculated with a Fusarium graminearum PH-1 strain for DON production. The solvent system for crude extraction was acetonitrile-water（84：16, v/v）. A simple two-step silica gel column chromatography was employed to separate the DON mycotoxin from wheat culture, combined with preparative high performance liquid chromatography（preparative HPLC） to purify the compound. The solvent system for the second silica gel column chromatography was methylene chloride-methanol（17：1, v/v）, which provided a good elution effect selected on thin layer chromatography（TLC）. The target compound was identified by HPLC, and the chemical structure was confirmed by mass spectrometry（MS） and ~1H and ^（13）C nuclear magnetic resonance（NMR） spectroscopy. A total of 433 mg of purified DON was obtained from 1 kg of wheat culture, with a purity of 99.01%. The study had provided an easy-operating and cost-effective method to isolate an expensive compound in a simple way.

Separation of liquefied product of Salix psammophila by column chromatography and structure analysis of its components

The liquefied product of Salixpsammophila wood was separated by thin-layer chromatography （TLC） and column chromatography, and its structure was identified by nuclear magnetic resonance （NMR） spectra in our study. The separation result indicates that the sample of liquefied S. psammophila contained at least two categories of components. The structure of the main components was guaiacyl C-1, C-2 of the hydroxyphenyl propane, i.e., the aromatic nucleus protons of lignin. Degradation and polycondensation reactions occurred when the S. psammophila wood was liquefied in phenol. Polycondensation reactions occurred among the depolymerization products from cellulose, the aromatic depolymerization products from lignin and the products of the displacement reactions between phenoxide ion and cellulose.

Separation of Felted Explosives by Pressurized Microemulsion Electrokinetic Chromatography

A new MEEKC method assisted with pressure-driven mobile phase was presented for the separation of felted explosives. Microemulsion solution was composed of 80 mmol/L heptane -120 mmol/L SDS (sodium dodecyl sulphate) - 900 mmol/L butanol - 10 mmol/L borate at pH 9.4 and a pressure-driven flow of 0.020 mL/min under 1.3 MPa was employed to manipulate the separation. Explosives HMX (1, 3, 5, 7-tetranitro-l, 3, 5, 7-tetrazacyclooctane) and TATB (triamino-trinitrobenzene), which were felted on fluorine rubber F2311 (polytrifluorochlorethylene and polyvinylidene fluoride 1/1 co-polymerization) and F2314 (polytrifluorochlorethylene and polyvinylidene fluoride 4/1 co-polymerization) were well separated with very good peak shapes.

MULTIDIMENSIONAL GAS CHROMATOGRAPHY FOR THE SEPARATION OF TCDD ISOMERS

A multidimensional gas chromatographic technique with heartcutting was used for the determination of complex isomeric mixtures of tetra- chlorodibenzo-p-dioxins(TCDDs)which could not be completely separated on a single capillary column.When using so-called heartcutting technique ,only the interested single peak or section of the fraction eluting from the first column was transferred onto the second column with different stationary phase.Flame ionization detection was used as the monitor detector and electron capture detection as the main detector.This arrangement offers complete separation and avoids interference of the possible remained chlorinated solvents.The separation power of multi- dimensional GC was demonstrated by the determination of TCDD isomers.

Entropy Increase and Nature of Separation

The entropy increase (EI) and the entropy increase per unit time (EIPUT) of the solute zone are chosen as new criteria of separation efficiency in chromatography and electrophoresis. It is verified by grand canonical ensemble (GCE) that the kinetic energy distribution of the solute is a common characteristic of the entropy and the distribution of solute zones.Under the assumptions. EI of the solute system is directly proportional to the logarithm of the difference between one and one half of the substantial separation ratio. the ratio of moles of a sparated solute to its total moles. and EIPUT is direchy proportional to corrected separation rate of separation system. EI or EIPUT is a important bridge between separation efficiency of chromatography or electrophoresis and operating parameters, especially. when nonequilibriumthermodynamics(NET) would be adopted.

AN EFFICIENT AND TARGET-ORIENTED SAMPLE ENRICHMENT METHOD FOR PREPARATIVE SEPARATION OF MINOR ALKALOIDS BY PH-ZONE-REFINING COUNTER-CURRENT CHROMATOGRAPHY

A sample enrichment method focusing on the minor targeted components was established to help them to be successfully separated by pH-zone refining CCC.Seven minor indole alkaloids in Uncaria rhynchophylla(Miq.)Miq.ex Havil(UR)were chosen to show the advantage of this method.The sample enrichment and separation were

A crosslinked chiral stationary phase for the separation of enantiomers by gas and supercritical fluid chromatography

Crosslinking experin(?)tnts for the chiral stationary phase OV-225-L-Val-t-butylamide within both fused silica and glass capillary columns have been carried out.Amino acid enantiomers were separated on crosslinked columns by、both GC and SFC methods.In SFC,the α values of amino acid enantiomers are independent of the density of the mobile phase,and they are hig her than those obtained by GC for the tested enantiomers with the same column due to the lower column tempera- ture used in SFC.

A nanocomposite consisting of silica-coated magnetite and phenyl-functionalized graphene oxide for extraction of polycyclic aromatic hydrocarbon from aqueous matrices

In this study,graphene oxide was covalently immobilized on silica-coated magnetite and then modified with 2-phenylethylamine to give a nanocomposite of type Fe3O4@SiO2@GO-PEA that can be applied to the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons（PAHs） from water samples.The resulting microspheres（Fe3O4@SiO2@GO-PEA） were characterized by Fourier transform-infrared spectroscopy（FT-IR）,scanning electron microscopy（SEM）,CHNS elemental analysis,and vibrating sample magnetometry（VSM） techniques.The adsorbent possesses the magnetic properties of Fe3O4 nanoparticles that allow them easily to be separated by an external magnetic field.They also have the high specific surface area of graphene oxide which improves adsorption capacity.Desorption conditions,extraction time,amount of adsorbent,salt concentration,and pH were investigated and optimized.Following desorption,the PAHs were quantified by gas chromatography with flame ionization detection（GC-FID）.The limits of detection（at an S/N ratio of 3） were achieved from 0.005 to0.1 μg/L with regression coefficients（R2） higher than 0.9954.The relative standard deviations（RSDs） were below 5.8%（intraday） and 6.2%（inter-day）,respectively.The method was successfully applied to the analysis of PAHs in environmental water samples where it showed recoveries in the range between 71.7%and 106.7%（with RSDs of 1.6%to 8.4%,for n = 3）.The results indicated that the Fe3O4@SiO2@GO-PEA microspheres had a great promise to extraction of PAHs from different water samples.