[Determination of oleanic acid and paeoniflorin in Paeonia lactiflora by ultrasound-assisted ionic liquid-reversed phase liquid chromatography].

Four kinds of ionic liquids [BMIM] Br, [BMIM] BF4, [BMIM] PF6, [HMIM] PF6 were used to analyze the content of oleanic acid and paeoniflorin in Paeonia lactiflora with ultrasonic-assisted extraction coupled with HPLC. The chromatographic column, Purospher star RP-C18 (4.6 mm x 250 mm, 5 µm), was used. Acetonitrile and water (90:10) as mobile phase was used to determine the content of oleanic acid with a gradient elution and flow rate at 1.00 mL · min(-1), detection wavelength at 210 nm, chromatographic column temperature at room temperature. Paeoniflorin content was determined using acetonitrile and water (18:82) as mobile phase with a gradient elution and flow rate at 1.00 mL · min(-1), detection wavelength at 250 nm, the chromatographic column temperature at room temperature. The result show that oleanic acid has the highest extraction yield when the conditions are solid-liquid ratio of 1:80 (g · mL(-1)), and the [BMIM] Br methanol solution concentration of 0.6 mol · L(-1). Under the optimal extraction conditions, the content of oleanic acid from 0.24 to 3.76 µg showed a good linearity (r = 0.9999), the average recovery was 97.20%. Paeoniflorin has the highest extraction yield when the conditions are solid-liquid ratio of 1:130 (g · mL(-1)), and the [C4 MIM] PF6 methanol solution concentration of 0.6 mol · L(-1). Under the optimal extraction conditions, paeoniflorin content from 0.42 to 4.20 µg showed a good lin- earity (r = 1.000), the average recovery was 98.84%. This method is simple and reliable, its repeatability is also very good. It has important significance in the study P. lactiflora of ionic liquid microextraction.

ZnO nanotubes supported molecularly imprinted polymers arrays as sensing materials for electrochemical detection of dopamine.

In this study, ZnO nanotubes (ZNTs) were prepared onto fluorine-doped tin oxide (FTO) glass and used as supports for MIPs arrays fabrication. Due to the imprinted cavities are always located at both inner and outer surface of ZNTs, these ZNTs supported MIPs arrays have good accessibility towards template and can be used as sensing materials for chemical sensors with high sensitivity, excellent selectivity and fast response. Using K3[Fe(CN)6] as electron probe, the fabricated electrochemical sensor shows two linear dynamic ranges (0.02-5µM and 10-800µM) towards dopamine. This proposed electrochemical sensor has been applied for dopamine determination with satisfied recoveries and precision. More complex human urine samples also confirmed that the proposed method has good accuracy for dopamine determination in real biological samples. These results suggest potential applicability of the proposed method and sensor in important molecule analysis.

Molecularly imprinted solid phase extraction method for simultaneous determination of seven nitroimidazoles from honey by HPLC-MS/MS.

In this work, a selective sample cleanup procedure that combined molecular imprinting technique with solid phase extraction was developed for the simultaneous extraction of the seven nitroimidazoles (NMZs) from honey samples. The molecular imprinting polymers for NMZs were prepared through bulk polymerization method using 2-methyl-5-nitroimidazole as template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross linking agent. The obtained molecular imprinting polymers showed high affinity to template molecule and was used as selective sorbent for simultaneously selective extraction of the seven NMZs from honey matrix. An off-line molecularly imprinted solid phase extraction (MISPE) method followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) for simultaneous determination of the seven NMZs from honey samples was also established. The proposed method was validated at 1.0, 2.0 and 10.0µg/kg, obtaining recoveries in the range of 79.7-110%, with repeatability and interday precision values (expressed as relative standard deviation) ≤11.4% and ≤15.2%, respectively. Limits of quantification for different NMZs were 1.0µg/kg, which were always below the minimum required performance limits established by the European Community Reference Laboratories (Commission Decision 2002/657/EC). It was demonstrated that this proposed MISPE-HPLC-MS-MS method could be applied to direct determination of NMZs from honey samples.

Molecularly imprinted polymer for selective extraction of domoic acid from seafood coupled with high-performance liquid chromatographic determination.

In this work, a highly selective sample cleanup procedure that combining molecular imprinting technique (MIT) and solid phase extraction (SPE) was developed for the isolation of domoic acid (a fascinating marine toxin) from seafood samples. The molecular imprinting polymer (MIP) for domoic acid was prepared using 1,3,5-pentanetricarboxylic acid as the template molecule instead of domoic acid. 4-Vinyl pyridine was used as the functional monomer and ethylene glycol dimethacrylate was used as the cross-linking monomer. The obtained imprinted polymer showed high affinity to domoic acid and was used as selective sorbent for the SPE of domoic acid from seafood samples. An off-line molecularly imprinted solid phase extraction (MISPE) method followed by high-performance liquid chromatography (HPLC) with diode-array detection for the detection of domoic acid was also established. Good linearity was obtained from 0.5 mg L(-1) to 25 mg L(-1) (R(2)>0.99) with a quantitation limit of 0.1 mg L(-1), which was sufficient to determine domoic acid at the maximum level permitted by several authorities. The mean recoveries of domoic acid from mussel extracts were 93.4-96.7%. It was demonstrated that the proposed MISPE-HPLC method could be applied to direct determination of domoic acid from seafood samples.

[Isolation, identification and diversity analysis of petroleum-degrading bacteria in Shengli Oil Field wetland soil].

The petroleum-degrading bacteria in Shengli Oil Field wetland soil were isolated and identified by traditional experiment methods, and their diversity was analyzed by PCR-DGGE (denaturing gradient gel electrophoresis). A total of thirteen petroleum-degrading bacterial strains were isolated, among which, six strains were found to have the ability of degrading the majority of C12-C26 petroleum hydrocarbon, with a degradation rate of > 90%. These petroleum degraders were phylogeneticly identified as the members of Halomonas, Alcanivorax, and Marinobacter, which were all belonged to gamma-proteobacteria. The uncultured predominant bacteria in Shengli Oil Field wetland soil were of Sulfurovum, Gillisia and Arcobacter. Among the predominant bacteria, gamma-proteobacteria accounted for a larger proportion, followed by alpha-proteobactiria, epsilon-proteobactiria, Actinobacteria, and Flavobacteria.

Molecularly imprinted polymer as SPE sorbent for selective extraction of melamine in dairy products.

In this paper, a highly selective sample cleanup procedure combining molecular imprinting and solid-phase extraction (MI-SPE) was developed for the isolation of melamine in dairy products. The molecularly imprinted polymer (MIP) was prepared using melamine as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linking monomer. The melamine imprinted polymer was used as selective sorbent for the solid-phase extraction of melamine from dairy products. An off-line MI-SPE method followed by high-performance liquid chromatography with diode-array detection for the detection of melamine was also established. The mean recoveries of melamine from ultra-heat treatment (UHT) milk and milk powders were 92.9-98.0% and 91.6-102.8%, respectively. Good linearity was obtained from 0.5 microM to 10 microM (r>0.999) with a quantitation limit of 0.5 micromol/L (0.06 ppm) which was sufficient to analyse melamine at the maximum level permitted by U.S. Food and Drug Administration (1 ppm) in dairy products. It was demonstrated that the proposed MI-SPE-HPLC method could be applied to direct determination of melamine in dairy products.