Review of advances in the thin layer chromatography of pesticides: 2004–2006

Applications of thin layer chromatography and high performance thin layer chromatography for the separation, detection, and qualitative and quantitative determination of pesticides, other agrochemicals, and related compounds are reviewed for the period from July 1, 2004 to November 1, 2006. Analyses are covered for a variety of samples, such as food, crops, biological, environmental, pharmaceuticals, and formulations, and for residues of pesticides of various types, including insecticides, herbicides, and fungicides, belonging to different chemical classes. In addition to references on residue analysis, studies such as pesticide-structure relationships, metabolism, degradation, and lipophilicity are covered, many of which make use of thin layer radiochromatography.     

Evaluation and validation of two different chromatographic methods (HPLC and LC-MS/MS) for the determination and confirmation of ochratoxin A in pig tissues

This study was undertaken to compare two different analytical methods for the determination and confirmation of ochratoxin A (OTA) in blood serum, kidney and liver of pigs. Sample clean-up was based on liquid-liquid phase extraction. The detection of OTA was accomplished with high-performance liquid chromatography (HPLC) combined either with fluorescence detection (FL) or electro spray ionization (ESI+) tandem mass spectrometry (MS–MS). Comparative method evaluation was based on the investigation of 90 samples of blood serum, kidney and liver per animal originating from different regions of Serbia. The analytical results are discussed in view of the respective method validation data and the corresponding experimental protocols. In general, analytical data obtained with (LC–MS–MS) liquid chromatography electro spray tandem mass spectro metry detection offered comparable good results at the sub-ppb concentration level. The results indicate that the liquid chromatography electro spray tandem mass spectrometric (LC-MS/MS) method was more specific and sensitive for the analysis and confirmation of ochratoxin A in pig tissues then high pressure liquid chromatography (HPLC) method after methylation of OTA.     

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.     

气相色谱法测定气田产出水中的甲醇含量

文章建立了使用气相色谱仪分析气田产出水中甲醇含量的方法。通过实验在设定不同分流比的情况下,能有效监测出气田产出水中不同浓度的甲醇含量,此方法灵敏度高,最低检出限为0.02%,测定气田产出水中甲醇加标回收率达到93%～94%。     

单标多点校正组合英蓝超滤测定地表水中多种阴离子

建立了利用组合单标多点校正和英蓝超滤单元的离子色谱法测定地表水中F-、C1-、NO3-、S0424—4-种离子的方法,方法操作简便,灵敏度高,线性范围广,抗干扰能力强,可同时快速测定不同数量级浓度的离子,降低了配置标准品和样品前处理的复杂性,减少了因前处理带来的干扰。     

Plant steroid hormones produced under Ni stress are involved in the regulation of metal uptake and oxidative stress in Brassica juncea L

Brassinosteroids (BRs) are involved in the amelioration of various biotic and abiotic stresses. With an aim to explore the role of BRs under heavy metal stress, plants of Brassica juncea L. were grown in pots. The plants were subjected to various concentrations of Nickel metal (0.0, 0.2, 0.4 and 0.6 mM) and harvested on 60th day in order to observe the expression of these hormones. The isolated BRs from the leaves of Brassica plants characterized by GC-MS include 24-Epibrassinolide (24-EBL), Castasterone, Dolicholide and Typhasterole. The effect of isolated 24-EBL was studied on Ni metal uptake and antioxidative defense system in 60 d old plants of Brassica. It was observed that 24-EBL significantly increased the activities of stress ameliorating enzymes and lowered the metal uptake in plants. This is the first report in B. juncea L. plants showing the expression of BRs under metal treatments and effect of the isolated 24-EBL on metal uptake and in oxidative stress management.     

The structure of the fire fighting foam surfactant Forafac®1157 and its biological and photolytic transformation products

For several decades, perfluorooctane sulfonate (PFOS) has widely been used as a fluorinated surfactant in aqueous film forming foams used as hydrocarbon fuel fire extinguishers. Due to concerns regarding its environmental persistence and toxicological effects, PFOS has recently been replaced by novel fluorinated surfactants such as Forafac®1157, developed by the DuPont company. The major component of Forafac®1157 is a 6:2 fluorotelomer sulfonamide alkylbetaine (6:2 FTAB), and a link between the trade name and the exact chemical structure is presented here to the scientific community for the first time. In the present work, the structure of the 6:2 FTAB was elucidated by ¹H, ¹³C and ¹⁹F nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. Moreover, its major metabolites from blue mussel (Mytilus edulis) and turbot (Scophthalmus maximus) and its photolytic transformation products were identified. Contrary to what has earlier been observed for PFOS, the 6:2 FTAB was extensively metabolized by blue mussel and turbot exposed to Forafac®1157. The major metabolite was a deacetylated betaine species, from which mono- and di-demethylated metabolites also were formed. Another abundant metabolite was the 6:2 fluorotelomer sulfonamide. In another experiment, Forafac®1157 was subjected to UV-light induced photolysis. The experimental conditions aimed to simulate Arctic conditions and the deacetylated species was again the primary transformation product of 6:2 FTAB. A 6:2 fluorotelomer sulfonamide was also formed along with a non-identified transformation product. The environmental presence of most of the metabolites and transformation products was qualitatively demonstrated by analysis of soil samples taken in close proximity to an airport fire training facility.     

采油废水中多环芳烃的生态风险评价

先利用C-18固相萃取小柱富集大港油田港东联合处理站污水处理站的采油废水中16种多环芳烃(PAHs,即萘、苊烯、苊、芴、菲、蒽、荧蒽、芘、、苯并[a]蒽、苯并[b]荧蒽、苯并[k]荧蒽、苯并[a]芘、茚并[1,2,3-cd]芘、二苯并[a,h]蒽和苯并[g,h,i]苝),再用气相色谱/质谱(GC/MS)分析测定其浓度,以评价PAHs的去除率和生态风险。结果表明:(1)采油废水经处理后,COD、石油类去除率分别达到82.27%、91.06%;外排水COD、石油类达到《污水综合排放标准》(GB 8978—1996)一级标准要求,优于中国采油废水处理的一般水平。(2)采油废水主要以2、3环的PAHs为主,约占总量的93%以上。(3)苯并[a]芘超过《地表水环境质量标准》(GB 3838—2002)中限值。(4)处理前的采油废水中蒽、菲和苯并[a]芘具有一定的生态风险;处理后的外排水中萘、蒽、菲、荧蒽、苯并[a]芘的暴露浓度(PEC)/预测无效应浓度(PNEC)均小于1,目前尚未对环境造成威胁。但是8种PAHs(苊烯和苯并类PAHs除外)总和表现出较大的毒性,需要引起重视。     

Determination of antibiotics in sewage from hospitals, nursery and slaughter house, wastewater treatment plant and source water in Chongqing region of Three Gorge Reservoir in China

Sewage samples from 4 hospitals, 1 nursery, 1 slaughter house, 1 wastewater treatment plant and 5 source water samples of Chongqing region of Three Gorge Reservoir were analyzed for macrolide, lincosamide, trimethoprim, fluorouinolone, sulfonamide and tetracycline antibiotics by online solid-phase extraction and liquid chromatography-tandem mass spectrometry. Results showed that the concentration of ofloxacin (OFX) in hospital was the highest among all water environments ranged from 1.660 μg/L to 4.240 μg/L and norfloxacin (NOR, 0.136-1.620 μg/L), ciproflaxacin (CIP, ranged from 0.011 μg/L to 0.136 μg/L), trimethoprim (TMP, 0.061-0.174 μg/L) were commonly detected. Removal range of antibiotics in the wastewater treatment plant was 18-100% and the removal ratio of tylosin, oxytetracycline and tetracycline were 100%. Relatively higher removal efficiencies were observed for tylosin (TYL), oxytetracycline (OXY) and tetracycline (TET)(100%), while lower removal efficiencies were observed for Trimethoprim (TMP, 1%), Epi-iso-chlorotetracycline (EICIC, 18%) and Erythromycin-H₂O (ERY-H₂O, 24%). Antibiotics were removed more efficiently in primary treatment compared with those in secondary treatment.     

Will photosynthetic capacity of aspen trees acclimate after long-term exposure to elevated CO2 and O3?

Photosynthetic acclimation under elevated carbon dioxide (CO₂) and/or ozone (O₃) has been the topic of discussion in many papers recently. We examined whether or not aspen plants grown under elevated CO₂ and/or O₃ will acclimate after 11 years of exposure at the Aspen Face site in Rhinelander, WI, USA. We studied diurnal patterns of instantaneous photosynthetic measurements as well as A/C_i measurements monthly during the 2004-2008 growing seasons. Our results suggest that the responses of two aspen clones differing in O₃ sensitivity showed no evidence of photosynthetic and stomatal acclimation under either elevated CO₂, O₃ or CO₂ + O₃. Both clones 42E and 271 did not show photosynthetic nor stomatal acclimation under elevated CO₂ and O₃ after a decade of exposure. We found that the degree of increase or decrease in the photosynthesis and stomatal conductance varied significantly from day to day and from one season to another.