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This paper presents a reliable method for simultaneous analysis of ten kinds of fatty acid methyl esters in biodiesel with high performance liquid chromatography equipped with diode array detector. The separation column was a Pursuit XRs C18 (250 mm×4.6 mm) and the mobile phase was a mixture of methanol and acetonitrile (80:20, V/V). The analytical performance parameters such as linearity, accuracy, precision, limit of detection and limit of quantification were discussed. The calibration curves of ten components show good linearity with the correlation coefficient greater than 0.99. The proposed method is time and cost-effective, which could be used for the determination of the FAMEs in the commercial biodiesel product.

Two kinds of hybrid ultraviolet (UV) photodetectors based on TiO2 nanocrystals capped with and without oleic acid (OA) and poly(9,9-dihexylfluorene) (PFH) were prepared from solution and characterized to study the effects of the surface ligand on the device function. Both devices showed obvious photovoltaic effect, high UV-sensitive photoconductivity, and fast response time. The hybrid device containing TiO2 nanocrystals with bare surface exhibited a photocurrent density of 91 μA/cm2 at zero bias under 3.2 mW/cm2 UV irradiation, corresponding to a photosensitivity of 28.4 mA/W. The other device containing OA-capped TiO2 nanocrystals showed a photocurrent density of 19 μA/cm2 and a photosensitivity of 5.9 mA/W under the same condition. It was found that capping TiO2 with OA had a beneficial effect on its solubility in organic solvent. On the contrary, a barrier might be formed, significantly influencing the charge-transfer behavior. This negative effect overcompensated the positive influence due to improved morphology and lowered the photosensitivity of the device.