| Objective:Paraquat is 2,2'-bipyridine weed killer,and is widely used in agriculture with high intoxicating events,or high death rate after misusing or paraquat suiciding. The factors related to prognosis in patients with paraquat intoxication are analyzed to approach the rational therapy and to decrease death rate of paraquat intoxication.A high performance liquid chromatography(HPLC) method was developed for determination of paraquat in rat plasma and tissues to provide evidence for the therapy and prognosis of paraquat-poisoned patients.Methods:1.Sample preparation:0.5 mL of plasma or tissues homogenate was centrifuged with 5000 r.min-1 for 5 min,then was placed in test tube,35%perchloric acid 100μL was added,mixed for 1 min,and centrifuged 5 min with high speed(10800 r.min-1) and low temperature.20μL supernatant was injected for analysis.2.Chromatographic condition:A Diamonsil TMC18 column(250 mm×4.6 mm,5μm) with the mobile phase consisted of 0.1 mol·L-1 phosphate buffer(75 mmol·L-1) sodium heptanesulfonate contained) -acetonitrile(88:12,V/V),pH adjusted to 3.0 by triethylamine was used to separate paraquat in biological samples,and the detection occurred at 258 nm.Results:1.The endogenous substances in blood plasma or tissues do not interfere with the determination of PQ in the method Established.2.A good linearity was obtained in the concentration range of 20-5000 ng·mL-1, The minimum quantitative limit was able to reach 20ng.mL-1.The absolute recovery was 87.5%,with RSD＜3%(n=5).The precisions of intra-day and inter-day(RSD) were both less than 7%(n=5).The relative recovery was 99.1%,with RSD＜3%(n=5).3.This method was applied to determine the PQ concentrations in rat plasma and tissues.After i.g 50 mg·kg-1,the concentration of paraquat in rat plasma was 360.3±130.9 ng·mL-1 at 8 h,and paraquat couldn't be detected in rat plasma at the third day.Similarly,after i.g 50 mg·kg-1,the PQ concentrations in the lung tissues declined slowly,even elevated after 24 hours,perhaps because of the pulmonary alveolus tissues which absorb and store up PQ,and introduce lung fibrosis;The PQ concentrations in the kidney tissues were much high whereas decreased quickly,but reduced slowly after 3 days;the PQ concentrations in the liver tissues were lower, compared to lung and kidney.No paraquat was detected in rat lung and liver tissues after 14 days,but it was undetectable after 28 days in rat kidney.Conclusion:1.Perchlodc acid was directly used to precipitate protein in plasma and tissues.The method was simple,quick,with complete precipitation and a high recovery,no disturbances in the determination.This method is able to meet the analysis requirement of biologic sample,and suitable for the PQ determination in rat plasma and tissues.2.According to PQ's structure feature and the chemical property,the opposition ion pair HPLC quantitative analysis method was ideal.This method uses phosphate solution as buffer solution,sodium heptanesulfonate as ion pair reagent,acetonitrile as the organic solvent,simultaneously the alkaloid triethylamine as pH modifier.The result indicated that the PQ peak shape was excellent,the retention time was suitable, and the analysis process was easy and feasible.3.The method established for PQ determination in rat plasma or tissues may further be used to evaluate the prognosis of PQ poisoning.
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