Field dissipation of oxyfluorfen in onion and its dynamics in soil under Indian tropical conditions

Oxyfluorfen, a diphenyl-ether herbicide is being used to control annual and perennial broad-leaved weeds and sedges in a variety of field crops including onion. The present study was aimed to investigate the dynamics and field persistence of oxyfluorfen in onion plant, bulb and soil under Indian tropical conditions. Application of four rates of oxyfluorfen viz., 200, 250, 300 and 400 g AI ha^?1 as pre-emergence gave good weed control in field experiment with onion. The oxyfluorfen residue dissipated faster in plant than in soil respectively, with a mean half-life of 6.1 and 11.2 days. Dissipation followed first-order kinetics. In laboratory column leaching experiments, 17 percent of the applied oxyfluorfen was recovered from the soil and indicates its solubility in water and mobility in sandy clay loam soil was low. A sorption study revealed that the adsorption of oxyfluorfen to the soil was highly influenced by the soil organic carbon with the K_oc value of 5450. The study concludes that the dissipation of oxyfluorfen in soil and onion was dependent on the physico-chemical properties of the soil and environmental conditions.     

Biodegradation of chlorpyrifos by either single or combined cultures of some soilborne plant pathogenic fungi

Abstract

Biodegradation of chlorpyrifos was studied in liquid culture media amended with either single or combined eight different plant pathogenic fungi isolated from the continuous cropping wheat fields. The average recovery of chlorpyrifos from the liquid media was found to be 86.1%. The detection limit of chlorpyrifos by the analytical method used was 19 ppb. Data showed that the growth of mixed fungi at concentrations up to 200 ppm of chlorpyrifos was higher than in the control treatment. Chlorpyrifos concentrations declined in the medium of combined fungi more than it did in the medium of any single fungus with increase in the incubation period. The amount of chlorpyrifos recovered was 79.8 ppm (39.9%) in the combined fungal cultures after 21 days. However, those recovered from the media of Fusarium graminearum, F. oxysporum, Rhizoctonia solani, Cladosporhim cladosporiodes, Cephalosporium sp., Trichoderma viridi, Alternaria alternata, and Cladorrhinum brunnescens, ranged from 48.0 to 74.8%. The half‐life value (T_1/2) for chlorpynfos was 15.8 day in the medium amended with mixed fungi. However, for the single cultures it ranged from 19.3 to 33.0 day.     

气相色谱法测定水中的2，4-二硝基氯苯

采用苯萃取,HP-624 30 m×0.53 mm×3.00 μm大口径毛细管柱分离,电子捕获检测器(ECD)检测2,4-二硝基氯苯,得到了良好的分离效果、较宽的线性关系和较高的灵敏度.     

等度洗脱快速分离SO4^2-、PO4^3-的新方法和

多聚磷酸盐在分离柱上保留能力强，不易洗脱，因此采用离子色谱分析测定多聚磷酸盐时大多采用梯度淋洗的方法，实现多聚磷酸盐、硫酸盐的分离。具体方法为采用美国戴安ICS-1000型离子色谱仪，METROSEP A Supp 5 100型分离柱，36mmol LiOH＋2％乙腈的淋洗液等度淋洗；进样20μL，流速0．7mL／min，8min内实现SO4^2-：PO4^3-和P2O7^4-的完全分离，保留时间分别为3．9，4．9和6．4min；检出限分别为4、11和17ng／L；加标回收率分别为96．88％，96．41％和98．48％。     

N-乙基吡啶溴对秀丽隐杆线虫生殖与脂代谢的多世代与跨世代效应

离子液体(ILs)的毒物兴奋效应(hormesis)使其低浓度、长期暴露的生态危害备受关注。本文以N-乙基吡啶溴(Br)作为ILs代表,以秀丽隐杆线虫为受试生物,开展连续多世代与跨世代生殖毒性效应研究,并从脂代谢酶、代谢中间产物探索其潜在机理。研究结果表明,在连续暴露的11代中,Br在0.53 mg·L^-1水平对F1、F2、F3、F7、F8、F9和F10代线虫生殖产生刺激效应,在F6和F11中产生抑制效应;在53 mg·L^-1水平,在更多世代中表现出抑制效应,并且抑制水平比低浓度更强。跨世代效应中,Br对F1脱离暴露的后代T3的生殖效应在高、低浓度均表现为抑制效应;同时,Br在低浓度连续11代暴露后,对其脱离暴露的后代T3’的生殖依然表现出刺激效应;但Br在高浓度多世代暴露后,对T3’无显著残留效应。在F1~F11代中,Br对三酰基甘油(TG)、乙酰辅酶A(ACA)、磷酸甘油酰基转移酶(GPAT)、肉碱棕榈酰转移酶(CPT)等脂代谢物、代谢酶活性的多世代效应也表现为刺激、抑制效应的波动变化,各生化指标效应之间以及与生殖效应之间均存在密切关联,并存在高低浓度效应差异。在T3、T3’中,Br对脂代谢物、脂代谢酶表现出显著的跨世代残留效应。综上,Br连续多世代暴露的生殖毒性及其在脱离暴露后代中的残留效应,均与脂代谢密切相关,并受到暴露浓度的显著影响。     

加速溶剂萃取-旋蒸定容-高效液相色谱法检测土壤中16种多环芳烃

建立了加速溶剂萃取-旋蒸定容-高效液相色谱法检测土壤样品中16种多环芳烃（PAHs）的方法.旋蒸定容有效减少了污染物的引入,特别是萘、菲.研究了影响PAHs回收率的主要因素.优化后的条件为：萃取温度110℃,静态萃取时间3 min,冲洗量30%,氮气吹扫时间30 s,正己烷/丙酮（体积比2：1）为萃取液,1次静态萃取循环,弗罗里硅土柱为固相萃取小柱,正己烷/二氯甲烷（体积比7：3）为淋洗液,淋洗液体积10 mL.在20-200 mg·L^-1范围内,各目标物线性关系（R²）为0.9994-1.目标物的检出限和定量限分别为0.08-2.50 mg·kg^-1和0.25-8.33 mg·kg^-1.在优化的实验条件下,加标水平为25 mg·kg^-1和100 mg·kg^-1时,目标物平均加标回收率分别为73.9%-105%、79.0%-110%,相对标准偏差（n=7）均小于10%.土壤PAHs QC样品的检测中,各目标物检测值均在参考值范围内;土壤PAHs QC样品加标回收率为63.4%-94.8%,适合实际土壤样品中多环芳烃的检测.

     

气相色谱法测定水和废水中丙烯腈

本文通过采用气相色谱法,以ＧＤＸ－５０２为固定相,ＦＩＤ为检测器测定水和废水中的丙烯腈,精密度和回收率高．方法简便易行,能满足行业废水和地面水的监队是水和废水中丙烯腈分析的较理想方法。     

Charge‐transfer chromatographic study of the interaction of commercial pesticides with hydroxypropyl‐β‐cyclodextrin

The interaction between 33 commercial pesticides with hydroxypropyI‐β‐cyclodextrin (HPBCD) was studied by charge‐transfer reversed‐phase thin‐layer chromatography using aqueous sodium chloride solutions as eluents. Each pesticide interacted with HPBCD, their lipophilicity linearly decreased with increasing HPBCD concentration, the pesticide ‐ HPBCD complex (probably inclusion complex) always being more hydrophilic than the uncomplexed pesticide. In many cases the retention of pesticide increased with increasing concentration of salt in the eluent. This effect can be tentatively explained by the suppression of the dissociation of the polar groups in the solute molecules resulting in increased apparent lipophilicity. No significant correlation was found between lipophilicity and complex stability or between salting‐out effect and lipophilicity, that is other than hydrophobic forces are involved in the pesticide ‐ HPBCD interaction.     

超高效液相色谱-四极杆飞行时间质谱测定沉积物中4种氯酚类物质

建立了一种固相萃取（SPE）-超高效液相色谱（UPLC）-四极杆飞行时间质谱（Q-TOF）测定沉积物中4种氯酚类物质苄氯酚（CP）、二氯酚（DCP）、六氯酚（HCP）、溴氯芬（BCP）的分析方法.样品用1%甲酸丙酮超声提取,强阴离子交换固相萃取柱净化富集,以Waters HSS C18柱（2.1 mm×100 mm,1.8 μm）为分离色谱柱,采用0.004%甲酸水（V：V）-甲醇作为流动相进行梯度洗脱,采用四极杆飞行时间质谱检测.结果表明,六氯酚和溴氯芬在0.2-5 μg·L-1,二氯酚在0.4-20 μg·L-1,苄氯酚在2-100 μg·L-1的范围内线性关系良好,相关系数均大于0.99.在3个加标浓度水平下,回收率为69.5%-99.6%,相对标准偏差为3.4%-14.8%.方法准确灵敏,可满足沉积物中氯酚类物质的测定.