| In this paper,the pre-treatment techniques and the chromatographic conditions of gas chromatography were studied in the detection of organochlorine pesticides in the Panax.The results were as follows:In this study,the way of ultrasonic extraction was used for the pre-treatment technology of Panax.The recovery was index,studying of solvents,solvent ratio,the sample size,solvent volume,total time of ultrasonic on the impact of pre-treatment.The experiment showed that the particle size was 100 mesh,the acetone:petroleum ether was 5:5,the total amount of solvent was 50 mL,and the total time of ultrasonic was 31 min.The recoveries were 80%to 120%.RSD was lower than 10%.The pre-treatment techniques met pesticide residue analysis.The study of the choice of capillary column showed that the weakly polar Phenomenex Zebron-2 separated the chromatography of organic chlorine better than the highly polar capillary column DB-WAX capillary column.For GC-FID chromatographic conditions,the effect of column flow and split ratio on the heptachlor gas chromatography conditions showed that when the split ratio was 60:1 and column flow was 1.95mL/min,correction factor(f)was the highest.When these conditions was applied for other six standards,only the peak of p,p'-DDT and o,p'-DDT were not good enough.The study of the split ratio and column flow of a-666 conditions showed that when the split ratio was 50:1 and column flow was 1 mL/min,correction factor(f)was the highest.When these conditions were used for other six standards,the results were good.The peak of GC is symmetrical,do not tailing,and the peak time is shorter.The peak of the order was ?-666,?-666,?-666,heptachlor,?-666,o,p'-DDT,p,p'-DDT.Under the conditions that split ratio was 50:1 and capillary flow rate was 1 mL/min,the impact of chromatography conditions research on final temperature,initial temperature,temperature programmed rate of 0.1mg/mL organochlorine standards.Experimental results showed that the chromatographic conditions were as follows:injection volume was 1?L;injector temperature was 250?,temperature-programmed initial temperature was 200?,heating rate was 15?/min,final temperature was 240?,maintaining 10min;detector temperature was 325?,split ratio was 50:1;capillary column flow rate was 1.00 mL/min.The peak of GC was good,not tailing.Retention time was shorter.The order of the peak were ?-666,?-666,?-666,heptachlor,?-666,o,p'-DDT and p,p'-DDT.For GC-ECD chromatographic conditions,the effect of the initial temperature and final temperature on chromatographic conditions showed that:when the sample volume was 1?L;the concentration of organochlorine was 0.1 ?g/mL;the Inlet temperature was 250?;initial temperature was 180?;heating rate 15 ?/min;final temperature was 230?;maintaining 20 min;detector was 300?;split was 20:1;capillary flow is 1 mL/min,the effects were good.The order of the peak were ?-666,?-666,?-666,heptachlor,?-666,o,p'-DDT and p,p'-DDT.Both the chromatography of FID detector and the ECD detector had the same order.The concentration of standards organochlorine pesticides were 0,0.005,0.01,0.05,0.1,0.5,1?g/mL.The r-value of the standard was as follows:0.9982,0.9923,0.9983,0.9989,0.9982,0.9992,0.9992 and 0.9978.The linear range was 2.38 × 10-13g?4.76 × 10-11g.In accordance with optimization method,the experiments were added high,medium and low standards.The average recoveries were 83.363%?110.13%.The RSD was 3.15%?7%.The chicken mushroom and pepper were selected to the optimal conditions of the experiment.The results showed that recoveries were 85.13%-110.34%;RSD were less than 10%,in line with pesticide residue analysis. |
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