ABSTRACT
Abstract A method for determination of trace mercury in water was established. The trace mercury in water was adsorbed quantitatively by activated carbon, and then determined by electrical pyrolysis atomic absorption spectrometry. In comparison with the detection methods of total mercury in water at present, the method avoids the steps of digestion, reduces the mercury pollution and the loss of the mercury, and is simple in operation. The effects of particle size of activated carbon, acid treatment method, acid medium and enrichment time on the enrichment efficiency were investigated. The effect of the pyrolysis temperature and the interfering ions on the determination results was investigated. Three standard addition procedures including activated carbon blank addition, solution blank addition and environmental water samples addition were studied. Regression correlation coefficients of three standard curves drawn by the three methods reached 0 . 9999 . The slope of the three standard curves had no difference by statistical test, indicating that the determination of mercury in environmental water samples under the experiment conditions was not interfered by the coexistent elements, which showed that the activated carbon blank addition method could be directly used for preparing standard curve of the method. The water samples containing 5 ng/L and 50 ng/L mercury were determined by the method, and the relative standard deviation were 7. 2% and 4. 2% (n=11), respectively, with a detection limit of 1. 2 ng/L. The recovery experiment was carried out after adding 10 ng/L mercury to the surface water and tap water samples, and the recoveries were between 92. 0% and 103. 0%. Analysis results were compared with ICP-MS as control and the deviation of the two methods were between 2 . 9% and 3 . 4%, indicating that the method was accurate and reliable, and had good precision.
ABSTRACT
ThevolatilecompositionsofDuchesneaindicawerestudiedbyheadspacesolid-phase microextraction ( HS-SPME ) , soxhlet extraction ( SE ) , ultrasonic assistant extraction ( UAE ) and steam distillation ( SD) coupled with gas chromatography-mass spectrometry ( GC-MS) . The experimental parameters of HS-SPME, including fiber type, extraction temperature, extraction time and desorption time were investigated. 47, 32, 16 and 16 compounds were identified by HS-SPME, SD, SE and UAE extracting methods, respectively. 66 compounds were obtained in total, among which 47 compounds were first reported in Duchesnea indica. The experimental results showed that terpenoids were the most abundant compositions in HS-SPME and SD, but acids accounted for 61. 44% and 69. 54% of the total content obtained by SE and UAE.