Papers by Keyword: High Performance Liquid Chromatography

Abstract: Analytical method has been developed and validated to determine free or leachable furfural concentration in wood-based panels. Particleboards obtained from birch wood and suberinic acids binder were chosen as a reference material. Two methods and two solvents were tested. Acetone extracts of the samples were analyzed with gas chromatography (GC) flame ionization detector system. Water extracts were analyzed with high-performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV) system. After the GC data in acetone extracts furfural concentration was below method limit of detection. HPLC-UV data showed that in water extracts furfural concentration was possible to determine. It was concluded that HPLC-UV is suitable and fast method for furfural determination in wood-based panels water extracts.

Abstract: Benzoic acid analysis in curry paste samples were carried out by using high performance liquid chromatography using ultrasonic extraction. Methanol-0.05 M ammonium acetate buffer pH 4.40 in the ratio of 55:45 (%v/v) at a flow rate of 1.00 mL/min was used as the mobile phase and benzoic acid detection was performed at 226 nm using an UV-Visible detector. Under the optimum conditions, linearity of spiked samples ranged from 50 to 3,000 mg/kg. Matrix matched calibrations had determined that benzoic acid contents in southern sour, red, and green curry paste samples were 67.59, 78.62 and 72.33 mg/kg, respectively. Recoveries were obtained from 89.34 to 101.70%, 83.37 to 130.30% and 92.75 to 113.56% with R.S.D. ranged from 2.71 to 6.53%, 4.02 to 11.58% and 5.81 to 6.35%, for southern sour, red, and green curry paste samples, respectively.

Abstract: To prepare immune-affinity column (IAC) of citrinin, CNBr activated Sepharose 4FF was used as a carrier to couple with monoclonal antibody against citrinin. A reversed-phase high performance liquid chromatography (HPLC) with fluorescence detection method was used to determine the samples elution after the IAC cleaning up. The fluorescence excitation and emission maxima of citrinin were 331 and 500 nm, respectively. Citrinin is determined by HPLC with a retention time of 6.5 min (flow rate of 1 mL/min) with acetonitrile-H₂O (45:55, v/v, pH 2.0). The linear range is 1-500 ng/mL. The column capacity is 0.35 μg when using 0.5 mL CNBr activated Sepharose 4FF and 500 μg monoclonal antibody against citrinin. Average recoveries of citrinin from red yeast rice spiked at levels of 0.1-0.6 mg/kg range from 74.2% to 87.12%. 16 samples of red yeast rice were determined by HPLC with immune-affinity column. The results show 12 samples contain citrinin, and concentrations of citrinin of red yeast rice are 100.6~443.6 μg/kg. The IAC method is found to be highly effective, sensitive and convenient for isolating the target analyte from samples.

Abstract: Using the high performance liquid chromatography (HPLC) method, bifenthrin isomers can be split at a polysaccharide derivatives chiral stationary phase column, and two well distinguished peaks of bifenthrin isomers are obtained. The effects of mobile phase ratios, temperatures, and detection wavelengths on the separation results are discussed. The optimal chromatographic conditions are as follows: the mobile phase ratio is methanol: ammonium acetate salts = 80:20, the column temperature is 35°C, and the wavelength is set as 220 nm. Under the optimal conditions, the resolution of bifenthrin enantiomer can be as large as 3.0.

Abstract: An ultrasound-assisted ionic liquid based dispersive liquid-liquid microextraction (UA-IL-DLLME) was developed for the determination of four plant hormones (6-benzyladenine (6-BA), kinetin (6-KT), 2, 4-dichlorophenoxy acetic acid (2, 4-D) and uniconazole (UN)) in soil, using high performance liquid chromatography (HPLC)-diode array detection (DAD). Several important parameters including the type and volume of extraction solvent, the volume of disperser solvent, ultrasound time, pH of the solution and salt effect were studied and optimized. Under optimum conditions, the limits of detections (LODs) for the target analytes were in the range of 0.002-0.01 μg g^-1. And satisfactory recoveries of the target analytes in the soil samples were 79.3-96.7 %, with relative standard deviations (RSD, n=5) that ranged from 4.3 to 6.7%.

Abstract: An in-situ polymerization method was used for the preparation of a novel stir bar based on neodymium magnet (Nd₂Fe₁₄B) powders. The processes were carried out by several steps including the enwrapping of Nd₂Fe₁₄B, the modification of the enclosed Nd₂Fe₁₄B, and the form of organic polymers on the surface of the modified powders. It was successfully used to enrich the plasticizers in water sample by stir bar sorptive extraction (SBSE). The experimental conditions for SBSE, such as the choice of extraction sorvents, salt concentration, extraction and desorption time were optimized in detail. Coupled to high performance liquid chromatography (HPLC), the recoveries of dibutyl phthalate (DBP), dimethyl phthalate (DMP), diethyl phthalate (DEP) were 89.2%~92.1%, 91.9%~96.6% and 94.3%~96.7%, respectively; the linear relationships between the concentration 5 μg/L and 800 μg/L for DBP were obtained; the limits of detection ranged from 0.09 μg/L to 0.21 μg/L in the optimal conditions.

Abstract: Basing on the HPLC fingerprints combined with chemo metric methods identified the Zherong Radix Pseudostellariae. Fingerprint of Radix Pseudostellariae by using HPLC was established in Fujian Zherong County, Guizhou Huangping County, Guizhou Kaili City 3 areas, combined with the fingerprint similarity evaluation software system analysis, results show that : The fingerprint similarity of Radix Pseudostellariae from different habitats were 0.887, 0.400, 0.464. The principal component analysis and cluster analysis identified Radix Pseudostellariae from different habitats by using SPSS software, the recognition of Zherong Radix Pseudostellariae accuracy rate reached 100%, the overall accuracy rate was 97.5%. Therefore, I think that HPLC fingerprinting combined with chemo metric method can accurately identify the zherong Radix Pseudostellariae and provide reliable technical support for the protection of geographical indication products.

Abstract: Based on the principle of solid phase extraction and the purification method using Florida silica, sixteen various kinds of polycyclic aromatic hydrocarbons such as naphthalene, acenaphthene and fluorene were measured in Urumqi snow by means of HPLC. The results showed that the concentration of PAHs was different in different sampling sites in Urumqi. The total concentration of PAHs was in the range of 0.2883 ~ 8.814 µg/mL and the content of PAHs snow was higher than that in water, which indicated that the snow was polluted by organic matters to a certain degree and the pollution was not so serious compared with the groundwater. So the snow has a certain application value for life.

Abstract: We established a method fordetermination of nitrate in water by High Performance Liquid Chromatography(HPLC). The sample was analysed by HPLC-ADA and was quantitated by externalstandard method after being simply processed. This methd has the advantages ofhigh separation efficiency and fast analysis. The experiment result showed thatthe linearly dependent coefficient was0.994, the recovery rate was between 98.7%～105.7%,the relative standard deviation（RSD）wasless than 2.1 %, and the lowest detectable limit is 0.01ng (S/N=1.6).

Abstract: The variation of carbonyl compounds in diesel exhaust at four loads before and after the treatment of Direct Non-thermal Plasma (DNTP) is studied with 2,4-dinitrophenylhydrazine (DNPH) derivatization method and high performance liquid chromatography (HPLC) analysis technique. The results show that the mass concentration of carbonyl compounds decreases firstly and then increases with the growing of diesel load before the treatment of DNTP. After the treatment of DNTP, the mass concentration of carbonyl compounds reduces remarkably. Maximum removal efficiency for total carbonyl compounds can reach 93.8% at 75% load. For acrolein, acetone, butyraldehyde and 2-butanone, removal efficiency can reach 100% at 25% load, 50% load and 100% load. At the same time, total ozone formation potential decrease dramatically.