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 Wysłany: Wto 9:34, 05 Kwi 2011 Temat postu: Base System - Microwave assisted extraction -HPLC- |
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Base System - Microwave assisted extraction-HPLC-ICP-MS determination of methylmercury in red shrimp
Step wave power extraction procedure (Psi ℃ hold time ll6o0 | 4040216oo 50202-3.1ICP-MS working conditions RF power: 1500W (shield torch sensitivity mode); Nebulizer: concentric nebulizer; spray chamber: quartz dual channel ; atomization temperature: a 5 ~ C; torch: Quartz integration; data collection mode: Integration time: Hg (205) 0.3s, Bif209) 0.3s; sampling depth: 8.0mm; carrier gas flow rate: 0 .86L/min; auxiliary gas flow rate: 0.40L/min. 2-3.2 chromatographic column: ZORBAXXDB-Cl8 Agilent, Shan State, 2.1mm × 50mm × 51. Lm); mobile phase: A 0.1% 2-mercaptoethanol, 2% methanol (v), 0.06mol / L ammonium acetate, the 0.45ixm filter membrane, ultrasonic 30min, degassing, spare; injection Volume: 20IxL; flow rate: 0.4mL/min. 68-2.3-3 microwave extraction conditions of a microwave instrument with temperature control of the experimental procedures, see Table 1. 2.4 Experimental procedure 2.4.1, respectively, the configuration of the solution volume of each of the above mentioned stock standard solution in 50mL 0.5mL volumetric flask, with secondary water to the mark, the preparation of lug / mL of standard working solution. Progressively diluted with secondary water, prepared into a concentration 0.5,1,2,4,10 ng / mL of standard working solution. 2.4.2 sample preparation system for a microwave-assisted extraction of alkali extraction method is accurate, the sample weighed 0.5g on the microwave digestion tank, add 25% KOH solution 6mL, according to the above microwave extraction conditions 1h, after extraction, the sample transferred to 50mL centrifuge tube, 5000r/min speed centrifugal 15min, supernatant was collected. Add 5mLCH2C extraction MeHg, the level of the oscillator oscillation 30min, 4000dmin speed centrifugal 10min, take the lower organic phase,[link widoczny dla zalogowanych], and then add the water phase 5mLCHzC, repeat the extraction process, combined organic phase solution extracted twice by adding 10mLHO, nitrogen filled, evaporation of organic phase, so that the methyl mercury remain in the aqueous phase, adjust the pH value to 6-8. Centrifuged again, supernatant was collected. Transferred to a 50mL volumetric flask with ultrapure water to volume. 0.2urn the membrane filter for use. 3. Results and discussion 3.1 standard curve and linear standard curve of methyl mercury in Figure 1 Figure 1 shows the curve of the linear equation was A = 452913C +25131, linear correlation coefficient r2 = 0.9993. Good linearity, a wide linear range. 3_2 detection limit of 3 times the signal to noise ratio limit of detection. The method detection limit of methylmercury 0.2ng/mL. 3.3 samples, the recovery and precision of the sample measured 3 times, had methylmercury, the average measured value of 0.039mg & g, accounting for the amount of total mercury in the red shrimp (0.05mg/kg) 78 %. The total amount of mercury measured by the ICP-MS 4. The method used to add the equivalent of adding recycling methods the level of 0.05mg & g analyte standard solution, according to the sample analysis steps to determine l1 times, calculate the recovery and precision. The recovery was 72-85% with RSD 9.8%. 4. Conclusion In this paper, a base system of a microwave extraction technique HPLC-ICP-MS determination of the red shrimp in the methylmercury concentrations, with satisfactory results. The method is simple pre-treatment, sample dissolution rate, the loss of methylmercury and other small features, combined with ICP-MS easy operation, high sensitivity, and can import and export of aquatic products to meet the rapid detection of methylmercury content requirements.
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