放射性同位素碳-14标记氯虫苯甲酰胺的合成与分析

以[14C]碳酸钡为放射性同位素原料,通过格氏反应、亲核取代、胺化和缩合等8步放化反应制备了2种放射性同位素碳-14标记的氯虫苯甲酰胺粗品,经反相高效液相色谱(RPHPLC)纯化获得标记物纯品14C-氯虫苯甲酰胺[3-溴-N-[4-氯-2-甲基-6-(甲氨基[羰基-14C]甲酰基)苯基]-1-(3-氯-2-吡啶基)-1H-吡唑-5-甲酰胺(2,55.6 mCi)和3-溴-N-[4-氯-2-甲基-6-(甲氨基甲酰基)苯基]-1-(3-氯-2-吡啶基)-1H-吡唑-5-[羰基-14C]甲酰胺(3,58.6 mCi)]。以[14C]碳酸钡计,两种标记物的总放化收率分别为32%和52%。其结构经核磁共振氢谱、质谱和在线放射性高效液相色谱(HPLC-FSA)分析确认。放射性薄层成像分析(TLC-IIA)、离线放射性高效液相色谱分析(HPLC-LSC)、在线放射性高效液相色谱-二极管阵列检测器/质谱联用(HPLCFSA/PDA/MS)和LSC分析表明,两种14C-氯虫苯甲酰胺的放化纯度分别为99.8%和99.6%,化学纯度分别为99.1%和98.4%,比活度分别为52.45 mCi/mmol和52.30 mCi/mmol。这2种标记物可作为放射性示踪剂,可满足氯虫苯甲酰胺在中国的登记代谢试验研究的需要。     

棉田除草剂溴嘧氯草醚的中试合成及杂质鉴定

为研究棉田除草剂溴嘧氯草醚(开发代号SIOC0426,化学名称为N-[2-氯-6-(4,6-二甲氧基-2-嘧啶氧基)苄基]-4-溴苯胺)的中试合成工艺,以2-氟-6-氯苯甲醛为起始原料,通过水解、缩合、还原和亲核取代反应在公斤级规模上合成了溴嘧氯草醚,用高效液相色谱外标法测定了原药含量,通过三维高效液相色谱-质谱联用(HPLC-DAD-MS)技术对原药中的杂质结构进行了鉴定。结果表明,反应总收率高于80%,原药含量大于98%,主要杂质为未反应完全的中间体2-[(4-溴苯氨基)甲基]-3-氯苯酚和溴嘧氯草醚Smiles重排产物。该工艺反应条件温和,反应收率高,原药含量高,"三废"排放较少,较适合工业化放大生产。     

14 C-标记腈菌唑的合成及其在小麦幼苗上的吸收与传导确证

以14C标记碳酸钡(Ba14CO3)为起始物,采用4步反应合成14C-1,2,4-三唑,总强度为5.813 1 mci,比强为15.53 μci/mg, 纯度大于99%,放化收率84.21%。在此基础上,参照文献报道的有关腈菌唑合成的方法,以4-氯苯乙腈为原料,经取代、缩合等3步反应合成了14C-腈菌唑,其总强度为0.556 6 mci,比强为2.53 μci/mg,纯度大于96%,放化收率85.4%。应用同位素示踪技术研究了14C-腈菌唑在2~3叶期小麦幼苗上的吸收、分布和传导。结果表明,根部给药后6~120 h,小麦根部放射性物质分布比例由59.88%下降为 24.87%;在幼苗茎基部和叶片中,放射性物质分布比例分别由14.18%、1.19%上升为 19.47%和33.75%;14C-腈菌唑被小麦幼苗吸收后向顶传导的速度很快,在叶片中的分布和积累与根部给药时间呈正相关,放射强度由2.94×10-6 μci上升为322.72×10-6 μci。放射性自显影表明,根部给药后120 h,14C-腈菌唑可以内吸传导到整个小麦植株。     

固相萃取-气相色谱-质谱联用法测定黄瓜和番茄中毒氟磷的残留及其裂解机理

建立了黄瓜和番茄中毒氟磷残留量的固相萃取-气相色谱-质谱联用(SPE-GC-MS)分析方法;对毒氟磷的裂解机理进行了探讨,确定了测试分析的定性离子和定量离子。样品采用V(正己烷):V(丙酮)=1:1混合液高速匀浆提取,使用以N-丙基乙二胺(PSA)、C18和石墨化炭黑(GCB)的混合物为填料的固相萃取柱净化,采用气相色谱-质谱联用仪在选择离子扫描(SIM)模式下进行检测,外标法定量。结果显示,毒氟磷在0.01~0.5 mg/L内,标准溶液的峰面积与质量浓度的线性关系良好(r≥0.999),方法的检出限(LOD)(S/N=3)为0.003 mg/kg,定量限(LOQ)(S/N=10)为0.01 mg/kg。在0.01、0.02和0.1 mg/kg添加水平下,毒氟磷的平均回收率为99.9%~100.2%,相对标准偏差(RSD,n=6)为0.97%~3.07%。     

德国2000年蜂蜜农药残留监控情况

类别被检测物质仪器方法检测限（μｇ /ｋｇ）检测样品数（个）杀虫剂氟氯苯菊酯氟胺氰菊酯双甲脒蝇毒硫磷高效液相色谱气 -质、气相色谱 (ＥＣＤ)气相色谱 (ＥＣＤ)气 -质、气相色谱 (ＥＣＤ)＜２＜１０＜６５＜３３９０９０９０７３杀螨剂溴螨酯乙酯杀螨醇气 -质、气相色谱 (ＥＣＤ)气 -质、气相色谱 (ＥＣＤ)＜３３＜３３９０７３杀菌剂ｃｙｍｉａｚｏｌ气 -质＜３８０９０磺胺类抗菌物质 磺胺嘧啶磺胺二甲嘧啶磺胺二甲氧嘧啶磺胺甲氧哒嗪液质联机液质联机液质联机液质联机＜２０＜２０＜２０＜２０９０抗生素链霉素土霉素金霉素脱氧土霉…     

QuEChERS-高效液相色谱-串联质谱法测定鲤鱼和小龙虾中毒氟磷残留

建立了鲤鱼和小龙虾中毒氟磷残留的QuEChERS-高效液相色谱-串联质谱检测方法。样品经乙腈提取,采用50 mg乙二胺-N-丙基硅烷 (PSA)、50 mg十八烷基键合硅胶(C₁₈)和50 mg无水硫酸镁分散萃取净化,以Eclipse XDB-C₁₈色谱柱分离待测物,采用电喷雾离子化正离子扫描和多反应监测模式 (MRM) 检测,以空白基质匹配标准溶液外标法定量。结果表明:在1.0~50 μg/L范围内,毒氟磷质量浓度与相应的峰面积间呈良好线性关系,相关系数均大于0.999,其在鲤鱼和小龙虾中的检出限 (LOD) 分别为0.4和0.8 μg/kg,定量限 (LOQ) 分别为2和3 μg/kg;在10、50和100 μg/kg添加水平下,鲤鱼和小龙虾2种基质中毒氟磷的日内和日间回收率为88%~103%,相对标准偏差 (RSD) 为1.2%~5.4%。该方法操作简便、经济、环保,能够满足鲤鱼和小龙虾中毒氟磷快速检测要求。     

超高效液相色谱串联质谱法测定马铃薯和土壤中氟啶胺残留

建立超高效液相色谱-电喷雾串联四极杆质谱快速测定马铃薯和土壤中氟啶胺残留的分析方法。样品经固相萃取净化,以液相色谱-质谱联用仪测定和确证,外标法定量。结果表明。该方法对氟啶胺的最低检出限为8μg／kg。在8．150-521．6μg／L线性范围内,相关系数为0．9999,回收率在81．96～116．66％之间,相对标准偏差〈10％（n=5）。     

氯虫苯甲酰胺和高效氯氟氰菊酯在豇豆和土壤中的残留行为

建立了采用分散固相萃取法进行样品前处理,分别用液相色谱-质谱联用和气相色谱检测14%氯虫苯甲酰胺·高效氯氟氰菊酯微囊悬浮剂中2种有效成分在豇豆和土壤中的残留量及消解动态的方法。结果表明:豇豆和土壤中分别添加0.005～1 mg/kg 4个水平的氯虫苯甲酰胺和高效氯氟氰菊酯,其平均回收率为80%～105%,相对标准偏差为0.70%～9.5%。北京和海南2地氯虫苯甲酰胺和高效氯氟氰菊酯在豇豆中的半衰期为4～6 d,土壤中的为10～24 d。成熟时采收,豇豆中氯虫苯甲酰胺和高效氯氟氰菊酯的残留量均低于0.2 mg/kg。推荐14%氯虫苯甲酰胺·高效氯氟氰菊酯微囊悬浮剂在豇豆上的使用剂量为有效成分45 g/hm2,使用方式为喷雾,施药次数不超过3次,施药间隔期为7 d,安全间隔期为5 d。     

分散固相萃取-超高效液相色谱-串联质谱法快速检测棉花和土壤中氟铃脲的残留

建立了分散固相萃取-超高效液相色谱-串联质谱快速检测棉花和土壤中氟铃脲残留的分析方法。样品采用乙腈提取,N-丙基乙二胺(PSA)净化,超高效液相色谱分离,电喷雾电离、负离子扫描,三重四级杆串联质谱检测以及基质匹配标准品的外标法定量。结果表明,在0.005~0.5 mg/kg 添加水平范围内,氟铃脲的平均添加回收率在71.1% ~110.0%之间,相对标准偏差在2.7% ~8.4%之间。该方法对土壤、棉叶和棉籽3种基质中氟铃脲的检出限 (LOD)分别为0.04,0.12,0.22 μ g/kg,定量限(LOQ)分别为0.14,0.41,0.74 μ g/kg。方法灵敏度高、操作简便、定量准确、测定浓度范围宽,可用于氟铃脲在棉叶、棉籽和土壤中的残留分析。     

高效液相色谱-串联质谱法快速检测马铃薯与土壤中氟醚菌酰胺残留

建立了采用QuEChERS为样品前处理方法的高效液相色谱-串联质谱（HPLC-MS/MS）快速检测马铃薯和土壤中氟醚菌酰胺残留的分析方法。样品经乙腈提取,PSA、C18吸附剂净化,电喷雾电离、正离子模式采集,多反应监测模式检测,基质匹配标准品外标法定量。结果表明:在0.002~1 mg/L范围内,氟醚菌酰胺在马铃薯等基质中的质量浓度与对应的峰面积间呈良好的线性关系,其相关系数均大于0.999 9。在 0.005~0.5 mg/kg添加水平下,氟醚菌酰胺在马铃薯、马铃薯植株和土壤中的日内平均回收率为81%~98%,日内相对标准偏差（RSD）为2.2%~13%（n = 5）;日间平均回收率为75%~106%,日间RSD为0.6%~11%（n = 15）。氟醚菌酰胺在马铃薯等基质中的定量限（LOQ）（S/N=10）均为0.001mg/kg。该方法简便、快速、准确,可用于马铃薯中氟醚菌酰胺的残留检测。     

Degradation of the herbicide [14C]-diclofop-methyl in soil under different conditions

The degradation of the herbicide diclofop-methyl, ( ± )-methyl 2-[4-(2,4-dichloro-phenoxy)phenoxy]propionate, was investigated in two agricultural soils under aerobic and anaerobic conditions. Using two differently labelled forms of [¹⁴C]-diclofop-methyl the qualitative as well as the quantitative formation of extractable metabolites was followed for 64 days. The mineralisation of the uniformly labelled aromatic rings was pursued by monitoring the ¹⁴CO₂ generated for 25 weeks. As a first step of the degradation a very rapid hydrolysis of the ester bond was detected under all conditions. Diclofop, the corresponding substituted propionic acid formed, was extensively degraded under aerobic conditions, the final product being ¹⁴CO₂. As an intermediate, a compound later identified by GLC/MS to be 4-(2,4-dichlorophenoxy)phenol, was found in the extracts. Furthermore, traces of six other unknown metabolites were detected. Under anaerobic conditions the degradation proceeded to a small extent. At most 3% of the applied radioactivity was accounted for by the degradation product 4-(2,4-dichlorophenoxy)phenol. No other metabolite, including ¹⁴CO₂, was observed, implying lack of any further degradation.     

The microbial biodegradation of paraquat in soil

The microbial degradation of [¹⁴C]paraquat using cultures from two agricultural soils was investigated. The experiments were carried out in the absence of light, under aerobic conditions. Degradation was rapid, with 50% mineralisation to [¹⁴C]carbon dioxide occurring within three weeks. HPLC, capillary electrophoresis and mass spectroscopy confirmed that the majority (>85%) of the remaining radiochemical in solution was [¹⁴C]oxalic acid, and that no paraquat remained.     

Influence of application methods on the degradation of permethrin in laboratory,soil aerobic metabolism studies

The effects of application rate, volume, solvent and soil moisture content on the kinetics of mineralization and degradation, of [¹⁴C] permethrin have been studied in a sandy loam soil under standard laboratory conditions. During the incubation period, up to 32 days, the temperature and moisture level of the soil were controlled. Apart from the effects of application rate, which have been widely reported, application volume had the most significant effect on mineralization rate and T_1/2. [¹⁴C]Permethrin, at a level of a 1 mg kg^?1 in the soil, applied in 100 μl of methanol, resulted in the evolution of 14% of the applied radiochemical as [¹⁴C] carbon dioxide over 30 days. The same level applied in 1000 μl mineralized at a faster rate, with 30% [¹⁴C]carbon dioxide evolved over 30 days. The test chemical applied to soil in methanol mineralized at a significantly faster rate than a similar concentration applied in ethanol. There was no significant difference when comparing applications made using acetonitrile with those using methanol or ethanol. The addition of formulation ingredients resulted in little or no variation in mineralisation rate compared to an equivalent application volume of methanol/water.     

Uptake and translocation of benomyl and carbendazim (methyl benzimidazol-2-yl carbamate) in the symplast

Cytoplasmic uptake of carbendazim (methyl benzimidazol-2-yl carbamate; MBC) from an aqueous solution was demonstrated with isolated mesophyll cells. About 2.5% of the labelled MBC (ring-2-[¹⁴C]) in the treatment solution (1.85 μg/ml) was taken up in 44 h. When cotyledons of cucumber seedling were treated with either 347 or 36 μg [¹⁴C]-MBC/plant 1.11 and 0.13% were extracted, respectively, from the remainder of the plant, 5 days after treatment. Greatest amounts were detected in shoot apices. Likewise, when MBC and benomyl were applied at the dose of 2 μmol, 0.34 and 0.57% were detected in the untreated part of the plant with a bioassay procedure. Foliar application with 347 or 36 μg[¹⁴C]-MBC/leaf resulted in the translocation of 1.68 and 0.11% out of the treated area. By scalding the living cells of the petiole translocation was prevented suggesting that long distance movement occurred in the symplast. During a period of 14 days 1.56% of [¹⁴C]-MBC applied to cucumber leaves was metabolised and respired as CO₂. This degradation was assumed to occur enzymically within the symplast.     

Acifluorfen metabolism in soybean: Diphenylether bond cleavage and the formation of homoglutathione, cysteine, and glucose conjugates

Metabolism of the substituted diphenylether herbicide, acifluorfen [sodium 5-(2-chloro-4-trifluoromethylphenoxy)-2-nitrobenzoate], was studied in excised leaf tissues of soybean [Glycine max (L.) Merr. ‘Evans’]. Studies with [chlorophenyl-¹⁴C]- and [nitrophenyl-¹⁴C]acifluorfen showed that the diphenylether bond was rapidly cleaved. From 85 to 95% of the absorbed [¹⁴C]acifluorfen was metabolized in less than 24 hr. Major polar metabolites were isolated and purified by solvent partitioning, adsorption, thin layer, and high-performance liquid chromatography. The major [chlorophenyl-¹⁴C]-labeled metabolite was identified as a malonyl-β- -glucoside (I) of 2-chloro-4-trifluoromethylphenol. Major [nitrophenyl-¹⁴C]-labeled metabolites were identified as a homoglutathione conjugate [S-(3-carboxy-4-nitrophenyl) γ-glutamyl-cysteinyl-β-alanine] (II), and a cysteine conjugate [S-(3-carboxy-4-nitrophenyl)cysteine] (III).     

Fate of [14C]diflubenzuron on cotton and in soil

Aqueous suspensions and oil emulsions of a commercial [¹⁴C]diflubenzuron (N-[[(4-chlorophenyl)amino]carbonyl]-2,6-difluorobenzamide) formulation (Dimilin W-25) remained on the leaf surface of greenhouse-treated plant tissues. Absorption, translocation, and metabolism of the [¹⁴C]diflubenzuron were not significant. Less than 0.05% of the applied ¹⁴C was found in newly developed plant tissues 28 days after spray treatment. [¹⁴C]Diflubenzuron was degraded in soil. After 91 days, biometer flask studies showed that 28% of the ¹⁴C incorporated into the soil as [¹⁴C]diflubenzuron was recovered as ¹⁴CO₂. Major dichloromethane-soluble soil residues were identified as unreacted [¹⁴C]diflubenzuron and [¹⁴C]4-chlorophenylurea. A minor unknown degradation product cochromatographed with 2,6-difluorobenzoic acid. Insoluble ¹⁴C-residues increased with time and represented 67.8% of the residual ¹⁴C in the soil 89 days after treatment. Cotton plants grown for 89 days in [¹⁴C]diflubenzuron-treated soil contained only 3% of the ¹⁴C applied to the soil. Small quantities of acetonitrile-soluble [¹⁴C]4-chlorophenylurea were isolated from the foliar tissues. Root tissues contained small amounts of [¹⁴C]diflubenzuron and trace quantities of a minor ¹⁴C-product that chromotographed similarly to 2,6-difluorobenzoic acid. Most of the ¹⁴C in the plant tissues (84–93%) was associated with an insoluble residue fraction 89 days after treatment.     

House fly head GABA-gated chloride channel: [3 H] α-Endosulfan binding in relation to polychlorocycloalkane insecticide action

This study attempts to use [³H] α-endosulfan to examine directly the binding site(s) for cyclodienes, lindane and toxaphene (collectively referred to as the polychlorocycloalkane or PCCA insecticides) in the 4-aminobutyric acid (GABA)-gated chloride channel. [³H] α-Endosulfan was prepared by reduction of hexachloronorbornenedicarboxylic anhydride with sodium borotritide, then coupling the labelled alcohol with thionyl chloride followed by HPLC purification (35 Ci mmol^?1, > 99% radiochemical purity). This new candidate radioligand readily partitions into lipid membranes and undergoes indiscriminate adsorption to surfaces resulting in high levels of non-specific binding. This makes it very difficult to differentiate the small portion of specific binding at the site relevant to toxic action. This problem was partially circumvented by incubating [³H] α-endosulfan (0.1 nM) with house-fly head membranes (0.2 mg protein) for 70 min at 22°C giving 23 (±4)% specific binding (40 fmol mg^?1 protein) determined as the difference between the radioligand alone and on preincubation for 15 min with unlabelled α-endosulfan (final concentration 100 nM). This procedure is not appropriate for determination of saturation isotherms and standard binding kinetics. However, the effectiveness of 16 PCCAs (also at 100 nM final concentration) in blocking the specific binding of [³H] α-endosulfan is generally consistent with their relative potencies as inhibitors of 4-[³H] propyl-1-(4-ethynylphenyl)-2,6,7-trioxabicyclo[2.2.2] octane ([³H]EBOB) binding suggesting that the binding site for both [³H]α-endosulfan and the PCCAs is part of the GABA-gated chloride channel. Insecticidal channel blockers of other types (e.g. picrotoxinin, trioxabicyclooctanes, a dithiane, and phenylpyrazoles) and GABA are poor inhibitors of [³H] α-endosulfan binding relative to their potencies as inhibitors of [³H] EBOB binding. It therefore appears that the PCCAs compete directly for the [³H] α-endosulfan site, whereas the other channel blockers bind with different inhibition kinetics or at a site more closely coupled to the EBOB than the α-endosulfan binding domain.     

Biodegradation of the herbicide bromoxynil and its plant cell wall bound residues in an agricultural soil

The mineralization and formation of metabolites and nonextractable residues of the herbicide [¹⁴C]bromoxyniloctanoate ([¹⁴C]3,5-dibromo-4-octanoylbenzonitrile) and the corresponding agent substance [¹⁴C]bromoxynil ([¹⁴C]3,5-dibromo-4-hydroxybenzonitrile) was investigated in a soil from an agricultural site in a model experiment. The mineralization of maize cell wall bound bromoxynil residues was also investigated in the agricultural soil material. The mineralization of [¹⁴C]bromoxynil and [¹⁴C]bromoxyniloctanoate in soil within 60 days amounted up to 42 and 49%, respectively. After the experiments, 52% of the originally applied [¹⁴C]bromoxynil and 44% of the [¹⁴C]bromoxyniloctanoate formed nonextractable residues in soil. Plant cell wall bound [¹⁴C]bromoxynil residues were also mineralized to an extent of about 21% within 70 days; the main portion of 76% persisted as nonextractable residues in the soil. In bacterial enrichment cultures and in soil two polar metabolites were observed; one of it could be identified as 3,5-dibromo-4-hydroxybenzoate and the other could be described tentatively as 3,5-dibromo-4-hydroxybenzamide.     

The degradation of diflubenzuron and its chief metabolites in soils. Part I: Hydrolytic cleavage of diflubenzuron

[¹⁴C]Diflubenzuron is readily degraded in various agricultural soils and in hydro-soil; 50% of the applied dose of 1 mg kg⁻¹ was metabolised in 2 days or less. The chief products of hydrolysis were identified as 4-chlorophenylurea and 2, 6-difluorobenzoic acid. A part of the radioactivity, increasing with incubation time, could not be extracted. Release from the soil of [¹⁴C]carbon dioxide, derived from both labelled phenyl rings, points to the ultimate mineralisation of diflubenzuron.