Determination of Fructose and Glucose Contents in Honey by Liquid Chromatography-refractive Index Detection Method and Direct Titration Method

In this study, fructose and glucose contents in honey were determined by liquid chromatography-refractive index detection method and alkaline copper tartrate solution-direct titration method. According to the results, there were great differences between determination results of reducing sugar contents by liquid chromatography-refractive index detection method and alkaline copper tartrate solution-direct titration method. Specifically, average determination results of reducing sugar contents by liquid chromatography-refractive index detection method were reduced by about 9.5% compared with alkaline copper tartrate solution-direct titra- tion method. Subsequently, determination results of reducing sugar contents by two methods were compared and analyzed. Liquid chromatography-refractive index detection method was used to determine fructose and glucose monomers in honey, but alkaline copper tartrate solution-direct titration method was used to determine reducing sugar composition in honey, which might lead to significantly different results. Due to small sample size and limited conditions, the determination results were not necessarily representative. Bee product acquisition and processing enterprises and relevant departments should pay much attention on these issues and fully consider the current situation of grass-roots units to develop scientific, rigorous, simple, universal, convenient, low-cost and practicable standards, thus ensuring the safety and reliability of food quality.

Separation and identification of moxifloxacin impurities in drug substance by high-performance liquid chromatography coupled with ultraviolet detection and Fourier transform ion cyclotron resonance mass spectrometry

In this paper, a high-performance liquid chromatography coupled with ultraviolet detection and Fourier transform-ion cyclotron resonance mass spectrometry （HPLC-UV/FrICRMS） method was described for the investigation of impurity profile in moxifloxacin （MOX） drug substance and chemical reference substance. Ten impurities were detected by HPLC-UV, while eight impurities were identified by using the high accurate molecular mass combined with multiple-stage mass spectrometric data and fragmentation rules. In addition, to our knowledge, five impurities were founded for the first time in MOX drug substance.

Determination of phenolic whitening agents in cosmetics by micellar electrokinetic capillary chromatography with amperometric detection

A sensitive method for simultaneous determination of six phenolic whitening agents, including arbutin, phenol, resorcinol, hydroquinone, kojic acid, and salicylic acid in cosmetics has been developed using micellar electrokinetic capillary chromatography with amperometric detection （MECC-AD）. Effects of several factors, such as the pH value and concentration of running buffer, potential applied to the working electrode, separation voltage, and injection time were investigated to obtain optimum conditions for separation and detection. With a 75 cm long fused-silica capillary tube, well-defined separation of six phenolic compounds was achieved in 10 mmol/L SDS/40 mmol/L H3BO3-Na2B407 running buffer （pH 9.0）. Good linear relationship was obtained for each analyte over three orders of magnitude with correlation coefficients （r2） between 0.9985 and 0.9994, and the detection limit （S/N = 3） ranged from 0.04 p^g/mL to 0.45 p^g/mL. The proposed method has been successfully applied for the determination of phenolic whitening agents in real cosmetic samples with satisfactory results, providing an alternative monitoring method for cosmetics safety regulation.

Separation and determination of pyrrolidinium ionic liquid cations by ion chromatography with direct conductivity detection

A method for rapid and simultaneous determination of multiple pyrrolidinium ionic liquid cations by ion chromatography with direct conductivity detection was developed.Chromatographic separations were performed on a cation exchange column using ethylenediamine-acetonitrile as the mobile phase.The effects of chromatographic column and the mobile phase,as well as the column temperature on the retention of the cations were investigated.The retention rules of the cations under different chromatographic conditions were formulated.The retention of the cations followed the carbon number rule.The method has been successfully applied to the determination of three ionic liquids synthesized by a chemical laboratory.

Imidazolium ionic liquid as the background ultraviolet absorption reagent for determination of morpholinium cations by high performance liquid chromatography-indirect ultraviolet detection

A novel analytical method was developed for determining morpholinium cations lacking ultraviolet absorption groups.This determination was carried out by high performance liquid chromatographyindirect ultraviolet（HPLC-1UV） detection using imidazolium ionic liquid as background absorption reagents,and imidazolium ionic liquid aq.soln.-organic solvent as mobile phase by a reversed-phase C18 column.The background ultraviolet absorption reagents,imidazolium ionic liquids and organic solvents were investigated.The imidazolium ionic liquid in the mobile phase is not only the background ultraviolet absorption reagent for IUV,but also an active component to improve the separation of morpholinium cations.It was found that morpholinium cations could be adequately determined when0.5 mmol/L 1-ethyl-3-methylimidazolium tetrafluoroborate aq.soln./methanol（80：20,v/v） was used as mobile phase with an IUV detection wavelength of 210 nm.In this study,the baseline separation of Nmethyl,ethylmorpholinium cations（MEMo） and N-methyl.propylmorpholinium cations（MPMo） was successfully achieved in 8.5 min.The detection limits（S/N = 3） for MEMo and MPMo were 0.15 and0.29 mg/L,respectively.This simple and practical method has been successfully applied to the determination of two morpholinium ionic liquids synthesized by the chemistry laboratory.

Bioautography and its scope in the field of natural product chemistry

Medicinal plants, vegetables and fruits are the sources of huge number of bioactive lead/scaffolds with therapeutic and nutraceutical importance. Bioautography is a means of target-directed isolation of active molecules on chromatogram. Organic solvents employed in chromatographic separation process can be completely removed before biological detection because these solvents cause inactivation of enzymes and/or death of living organisms. They offer a rapid and easy identification of bioactive lead/scaffolds in complex matrices of plant extracts. Bioautography is a technique to isolate hit（s）/lead（s） by employing a suitable chromatographic process followed by a biological detection system. This review critically describes the methodologies to identify antimicrobial, antioxidant, enzyme inhibitor lead/scaffolds by employing bioautography. A significant number of examples have been incorporated to authenticate the methodologies.

Fast analysis of thiocyanate by ion-pair chromatography with direct conductivity detection on a monolithic column

Fast analysis of thiocyanate by ion-pair chromatography using a silica-based monolithic column and direct conductivity detection was carried out. Chromatographic separation was performed on a Chromolith Speed ROD RP-18e using tetrabutylammonium hydroxide （TBA）-phthalic acid-acetonitrile as eluent. The effects of eluent concentration, eluent pH value, column temperature and flow rate on retention time of thiocyanate were investigated. The optimized chromatographic conditions for the determination of thiocyanate were as follows： 0.25 mmol/L TBA-0.18 mmol/L phthalate-7% acetonitrile （pH 5.5） as eluent, column temperature of 30 ℃, and flow rate of 6.0 mL/min. Retention time of thiocyanate was less than 1 min under the conditions. Common anions （Cl^-, NO3 , SO42 and I^- ） did not interfere with the determination of thiocyanate. Detection limit （S/N = 3） of thiocyanate was 0.96 mg/L. Calibration graph between peak area and the concentration of thiocyanate was linear in the range of 2.0- 100.0 mg/L. Relative standard deviation （RSD） of chromatographic peak area was 1.4% （n = 5）. This method has been applied to the determination of thiocyanate in ionic liquids. Recoveries of thiocyanate after spiking were 100.5%.

8-Hydroxydeoxyguanosine as a Biomarker of Oxidative DNA Damage Induced by Environmental Tobacco Side-stream Smoke and Its Mechanism

To study the genotoxicity effect of environmental tobacco side-stream smokes (ETSS) on oxidative DNA damage and its molecular mechanism. Methods DNA adduct 8-hydroxydeoxyguanosine (8-OHdG) was used as a biomarker of oxidative DNA damage. The level of 8-OHdG in DNA exposed to ETSS was detected by high performance liquid chromatography with electrochemical detection. Organic and inorganic components in ETSS were analyzed by gas chromatography-mass spectrum and atomic absorption spectrum respectively. Results Particle matters (PMs) and volatile organic compounds (VOCs) in ETSS could directly induce oxidative DNA damage and formation of 8-OHdG. There were 123 and 84 kinds of organic components in PMs and VOCs respectively, and 7 kinds of inorganic components in ETSS. Some components, especially quinones and polyphenols in ETSS, could produce free radicals in vitro by auto-oxidation without any biological activity systems, and with the catalytic reaction of metals, the DNA adduct 8-OHdG was produced. Conclusion ETSS have biological oxidative effect on DNA in vitro and in vivo, and expressed direct genotoxicity. 8-OHdG is a valuable biomarker of oxidative DNA damage.

A high-performance liquid chromatography with circular dichroism detector for determination of stereochemistry of 6, 9-oxygen bridge dibenzocyclooctadiene lignans from kadsura coccinea

The stereochemistry of two 6, 9-oxygen bridge dibenzocyclooctadiene lignans from Kadsura coccinea, are difficult to separate and very unstable. The present study was designed to develop a high-performance liquid chromatography using circular dichroism detection for the analysis of the stereochemistry. A new 6, 9-oxygen bridge dibenzocyclooctadiene lignans named Kadsulignan Q was firstly found with an S-biphenyl configuration. The other compound was identified as Kadsulignan L with an R- biphenyl configuration. In order to obtain kinetic data on their reversible interconversion, the stability was measured at different deuterated solvents such as deuterated methanol, deuterated chloroform and deuterated dimethylsulfoxide. The lignans were more unstable and converted more easily in deuterated methanol than in deuterated chloroform and deuterated dimethylsulfoxide.

The recombinant expression systems for structure determination of eukaryotic membrane proteins

Eukaryotic membrane proteins, many of which are key players in various biological processes, constitute more than half of the drug targets and represent important candidates for structural studies. In contrast to their physiological significance, only very limited number of eukaryoUc membrane protein structures have been obtained due to the technical challenges in the genera- tion of recombinant proteins. In this review, we examine the major recombinant expression systems for eukaryotic membrane proteins and compare their relative advantages and disadvantages. We also attempted to summarize the recent technical strategies in the advancement of eukaryotic membrane protein purification and crystallization.

Study on pharmacokinetics and tissue distribution of the isocorydine derivative (AICD) in rats by HPLC-DAD method

A simple and effective high-performance liquid chromatography with diode-array detection method coupled with a liquid liquid extraction pretreatment has been developed for determining the pharmacokinetics and tissue distribution of a novel structurally modified derivative (8-acetamino-isocorydine) of isocorydine. According to the in vivo experiments data calculations by DAS 2.0 software, a two compartment metabolic model was suitable for describing the pharmacokinetic of 8-acetaminoiso-corydine in rats. 8-Acetamino-isocorydine was absorbed well after oral administration, and the absolute bioavailability was 76.5%. The half-life of 8-acetamino-isocorydine after intravenous and oral administration was 2.2 h and 2.0 h, respectively. In Oro, 8-acetamino-isocorydine was highly distributed in the lungs, kidney and liver; however, relatively little entered the brain, suggesting that 8-acetaminoisocorydine could not easily pass through the blood brain bather. Our work describes the first characterization of the pharmacokinetic parameters and tissue distribution of 8-acetamino-isocorydine. The acquired data will provide useful infonnation for the in vivo pharmacology of 8-acetaminoisocorydine, and can he applied to new drug research. (C) 2015 Chinese Pharmaceutical Association and Institute of Materia IMedica, Chinese Academy of 'Medical Sciences. Production and hosting by Elsevier B.V.