The composition and antimicrobial activity of the essential oils which were obtained from agarwood originated from Aquilaria sinensis (Lour.) Gilg stimulated by the chemical method (S1) were characterized, taking wild agarwood (S2) and healthy trees (S3) respectively as the positive and negative controls. The chemical composition of S1 was investigated by gas chromatography-mass spectrometry (GC-MS). The essential oil of S1 showed a similar composition to that of S2, being rich in sesquiterpenes and aromatic constituents. However, the essential oil of S3 was abundant in fatty acids and alkanes. Essential oils of S1 and S2 had better inhibition activities towards Bacillus subtilis and Staphyloccus aureus, compared with essential oil of S3. Escherichia coli was not sensitive to any of them.

A sensitive and rapid multi-residue analytical method for plant growth regulators (PGRs) (i.e., chlormequat, mepiquat, paclobutrazol, uniconazole, ethephon and flumetralin) in apples and tomatoes was developed using high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). A homogenised sample was extracted with a mixture of methanol/water (90:10, v/v) and adjusted to pH <3 with formic acid. Primary secondary amine (PSA) adsorbent was used to clean up the sample. The determination was performed using electrospray ionisation (ESI) and a triple quadrupole (QqQ) analyser. Under the optimised method, the results showed that, except for ethephon, the recoveries were 81.8-98.1% in apples and tomatoes at the spiked concentrations of 0.005 to 2 mg/kg, with relative standard deviations (RSDs) of less than 11.7%. The limits of quantification (LOQs) were lower than their maximum residue limits (MRLs). The procedure was concluded as a practical method to determine the PGR residues in fruit and vegetables and is also suitable for the simultaneous analysis of the amounts of samples for routine monitoring. The analytical method described herein demonstrates a strong potential for its application in the field of PGR multi-residue analysis to help assure food safety.

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Investigations of the transfer of pesticide residues from tea to its infusion can be important in the assessment of the possible health benefits of tea consumption. In this work the transfer of difenoconazole and azoxystrobin residues from chrysanthemum tea to its infusion was investigated at different water temperatures, infusion intervals and times. The transfer percentages were in the range of 18.7-51.6% for difenoconazole and of 38.1-71.2% for azoxystrobin, and increased considerably with longer infusion intervals. The results indicated that azoxystrobin with a lower octanol-water partition coefficient of 2.5, showed a higher transfer than that of difenoconazole with a relatively high octanol-water partition coefficient of 4.4. Water temperature had no significant effect on the transfer of the two residues, and no obvious loss of difenoconazole and azoxystrobin occurred during the infusion process. The concentrations in the infusions decreased gradually from 0.67 to 0.30 μg kg(-1) for difenoconazole and from 2.3 to 0.46 μg kg(-1) for azoxystrobin after five infusions. To assess the potential health risk, the values of estimate expose risk were calculated to be 0.016 for difenoconazole and 0.0022 for azoxystrobin, meaning the daily residue intake of the two analytes from chrysanthemum tea was safe. This research may help assure food safety and identify the potential exposure risks from pesticides in chrysanthemum that may be health concerns.

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A novel amidoxime-based adsorbent of titaniummolybdopyrophosphate-g-amidoxime (TMP-g-AO) was prepared by chemical coprecipitation and subsequent chemical modifications. The successful grafting of acrylonitrile group and the subsequent conversion of acrylonitrile group to amidoxime groups were characterized by scanning electron microscopy-energy dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, N 2 −BET, and thermal analysis. The adsorption behavior of uranium(VI) on TMP-g-AO was investigated for low concentration uranium solution by batch experiments at a fixed pH of 8.2 ± 0.1. It is found that the adsorption rate of uranium from solution was 99.77% when the uranium concentration was 42.3 μg/L, pH = 8.2 ± 0.1, temperature = 298.15 K, and the adsorbent dosage = 0.05 g. The kinetic data follow the pseudo-second-order model, and adsorption equilibrium data fit the Langmuir model well. The thermodynamics parameters (ΔS, ΔH, and ΔG) indicate that the adsorption process is spontaneous and endothermic. The functional TMP-g-AO adsorbent exhibits good selectivity and affinity for uranium ions under coexisting multimetal ions except for Fe 3+ and Co 2+ . Desorption was performed, and the adsorption rate of uranium by TMP-g-AO only decreased 1.42% after five consecutive adsorption−desorption cycles. In order to evaluate the potential application of TMP-g-AO for uranium extraction from seawater, the experiments on adsorption of uranium(VI) from natural seawater and the uranium-doped seawater were conducted, and the adsorbent exhibited a high adsorption rate of uranium(VI). The results show that TMP-g-AO could be a very promising adsorbent for uranium extraction from seawater.

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