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As a result of the important roles of boron (B) in the growth of plants, the uptake of B by plants is dependent upon the existing form and content of available B in soil, which can bring about the local cycle of B isotope equilibrium. A method using water-heating extraction combined with three-step ion-exchange chromatography was developed for the extraction and isotopic analysis of available B in soil. The extraction efficiency and fractionation of B isotopic composition in the procedure were investigated. The results showed that, in the upper layers of soils, the change of δ11B values was opposite that of the mass concentration and a similar variation between δ11B and content occurred in the lower layers. The isotope of available B in soil can create a featured isotopic signature to further understand the geochemical details related to the soil properties and molecular mechanism of B uptake in plants.

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Non-equilibrium ultrasound-assisted solid–liquid extraction of boron present in different phases within plants.

An optimized analysis method based on headspace liquid phase microextraction (HS-LPME) and gas chromatography coupled with mass spectrometry was proposed for the determination of trihalomethanes (THMs) in drinking water. The response surface method (RSM) was used to optimize the extraction of THMs for analysis by HS-LPME. The temperature, extraction time and NaCl concentration were found to be important extraction parameters. The coefficient of determination (R 2 ) for the model was 94.97%. A high probability value (P a 0.0001) for the regression indicated that the model had a high level of significance. The optimum conditions were seen to be: temperature 42.08C, NaCl concentration 0.30 g/mL, and extraction time 28 min. The response variable was the summation of the THMs chromatography peak areas and the reproducibility of this was investigated in five replicate experiments under the optimized conditions. The relative standard deviations (RSD%) of the THMs ranged from 8.0 -11.6%. The limits of detection (LODs), based on a signal-to-noise ratio (S/N) of three ranged from 0.42 -0.78 lg/L, and were lower than the maximum limits for THMs in drinking water established by the WHO.