咪鲜胺及其代谢物2,4,6-三氯苯酚在金柑防腐保鲜贮藏中的残留动态及风险评估

建立气相色谱-串联质谱法同时测定经咪鲜胺浸泡处理的金柑中咪鲜胺和2,4,6-三氯苯酚的含量,分析不同浸泡质量浓度和时间对其残留量的影响和变化特征,并评估咪鲜胺的摄入风险。该方法对咪鲜胺和2,4,6-三氯苯酚的检出限、平均加标回收率和重复性（以相对标准偏差表示）分别为1.70 μg/kg、0.68 μg/kg,95.7%、98.1%,5.14%、3.89%。结果表明,咪鲜胺浸果质量浓度越高、时间越长,金柑中咪鲜胺及其代谢物2,4,6-三氯苯酚的残留量越大;咪鲜胺残留量先升高后缓慢降低,第3天达到峰值;在21 d贮藏期内,2,4,6-三氯苯酚含量持续升高。用质量浓度450 mg/L咪鲜胺溶液浸泡2 min（咪鲜胺农药登记使用方法）金柑,14 d咪鲜胺、2,4,6-三氯苯酚的含量分别为8.180、0.069 mg/kg;浸泡质量浓度增加至900、2 700 mg/L处理,即使在安全间隔期后的21 d咪鲜胺残留量仍高于柑橘类水果对咪鲜胺的最大残留限量值。安全间隔期14 d金柑咪鲜胺的慢性摄入风险在可接受的范围内,但急性摄入风险大于100.0%,为不可接受。     

花生中咪鲜胺及2, 4, 6-三氯苯酚残留量的测定

目的 建立气相色谱法测定咪鲜胺及其代谢产物2,4,6-三氯苯酚在花生中残留的分析方法。方法 样品采用乙腈-乙酸（99:1, 体积比）提取,采用QuEChERS净化方式,气相色谱仪进行测定。研究分析了不同溶剂,不同净化方式,不同仪器条件对咪鲜胺及2,4,6-三氯苯酚的提取净化影响。结果 在0.01~1.0 μg/mL线性范围内,咪鲜胺和2,4,6-三氯苯酚的线性均大于0.999,检出限为0.008 mg/kg,在添加水平为0.01、0.1 、0.5 mg/kg下,其回收率在81.2%~93.5%之间,RSD（n=7）为1.2%~4.9%。【结论】 该方法具有高效,快捷,灵敏,成本低廉的优点,适用于花生中咪鲜胺及其代谢产物2,4,6-三氯苯酚的分析。     

溶剂萃取-差示脉冲溶出伏安法测定橘皮中的邻苯基苯酚

建立溶剂萃取-差示脉冲溶出伏安法测定橘皮中的邻苯基苯酚(OPP)的方法。为避免橘皮中大量抗坏血酸和香精油等物质的影响,采用甲苯萃取橘皮中的OPP,在优化实验条件下,运用差示脉冲溶出伏安法测定橘皮中OPP含量。结果表明,OPP氧化峰电流与其浓度在2.0×10-9～4.0×10-6 mol/L范围内呈良好的线性关系,检出限达到8.1×10-10mol/L,回收率为106.7%～112.2%。该法操作简单、快速、灵敏、准确。     

气相色谱-串联质谱法快速测定水果中咪鲜胺及其代谢物2,4,6-三氯苯酚的残留量

目的：建立基质分散固相萃取-气相色谱-串联质谱法快速测定水果中咪鲜胺及其代谢物2,4,6-三氯苯酚残留量的方法。方法：采用以乙腈作提取剂、以N-丙基乙二胺和十八烷基硅烷键合硅胶（C18）作为混合固相基质分散萃取净化剂的前处理方法,并利用气相色谱-串联质谱在多反应离子监测模式条件下进行检测,用基质匹配标准品的外标法定量。结果：咪鲜胺及其代谢物2,4,6-三氯苯酚在0.004～0.400 mg/kg范围内线性关系均良好,相关系数分别为0.999 4和0.999 2;在3 个添加水平（0.01、0.02、0.10 mg/kg）范围内的平均回收率分别为80.1%～101.5%和79.0%～97.4%,相对标准偏差分别为2.8%～6.8%和2.0%～6.0%,方法的定量限分别为0.004 mg/kg和0.005 mg/kg。结论：该方法前处理简单快速、灵敏度高、测定线性范围宽,可用于水果中咪鲜胺及其代谢物2,4,6-三氯苯酚残留的快速测定。     

QuEChERS-气相色谱质谱联用法测定辣椒中的咪鲜胺及2，4，6-三氯苯酚残留量

建立QuEChERS(quick、easy、cheap、effective、rugged、safe)-气相色谱-质谱联用快速测定辣椒中咪鲜胺及其代谢物2,4,6-三氯苯酚残留量的方法。样品经乙腈-乙酸(99∶1,体积比)提取剂后,以无水硫酸镁和N-丙基乙二胺(primary secondary amine,PSA)净化,并利用气相色谱-串联质谱进行检测。研究不同提取溶剂和无水硫酸镁PSA量(3∶1,质量比)对提取净化效率的影响。结果表明:在最优试验条件下,咪鲜胺及其代谢物2,4,6-三氯苯酚在0.01μg/mL～1.00μg/mL范围内线性关系均良好,相关系数分别为0.999 1和0.999 2,检出限为0.003 3 mg/kg;在0.02、0.10、0.50μg/mL 3个添加水平下平均回收率为96.70%～100.64%,相对标准偏差(n=7)为2.33%～4.28%。该方法具有快速、便捷、安全、清洁和成本低的特点,可用于辣椒中咪鲜胺及其代谢物2,4,6-三氯苯酚残留的快速测定。     

气相色谱-三重四极杆质谱法测定粮谷中咪鲜胺及其代谢物残留量

目的建立粮谷中咪鲜胺及其代谢产物2,4,6-三氯苯酚残留测定的气相色谱-三重四极杆质谱(gas chromatography-triple quadrupole mass spectrometry, GC-MS/MS)的分析方法。方法试样加水涡旋混匀经1%乙酸乙腈提取,通过N-丙基乙二胺(primarysecondaryamine,PSA)、C18吸附剂、及增强型脂质去除产品(enhancedmoderemoval-lipid,EMR-lipid)净化提取液,以气相色谱-三重四极杆质谱多重反应离子监测模式(multiplereactionmonitoring,MRM)检测,外标法定量。结果 2,4,6-三氯苯酚在0.25~10.0μg/L、咪鲜胺在2.5~100.0μg/L范围下均具有良好的线性关系,相关系数(r2)均大于0.999, 2,4,6-三氯苯酚在0.5、1.0、2.0、5.0μg/kg的添加水平下回收率在80.2%~118.6%内,相对标准偏差在1.8%~8.8%内,定量限为0.5μg/kg;咪鲜胺在5.0、10.0、20.0、50.0μg/kg的添加水平下回收率在80.6%~115.5%内,相对标准偏差在1.8%~5.9%内;定量限为5.0μg/kg。结论该方法操作高效快捷、检测灵敏度高,抗基质效应强,适用于快速处理高通量粮谷中咪鲜胺及其代谢产物的残留量检测。     

气相色谱法检测苹果中氟环唑、咪鲜胺及其代谢物的残留

目的建立气相色谱法检测苹果中咪鲜胺及其代谢物2,4,6-三氯苯酚和氟环唑残留的分析方法。方法匀浆样品加入1%乙酸乙腈振荡,再加入3 g NaCl、2 g无水Na2SO4高速振荡10 min,以5000 r/min离心5 min提取,之后经N-丙基乙二胺(primary secondary amine,PSA)净化,采用气相色谱法进行检测,外标法定量。结果苹果中3种农药在0.01~2.0 mg/L范围内呈良好线性(r2=0.999)。方法定量限为10~20μg/kg。平均回收率为74%~108%,相对标准偏差为2.90%~9.55%。结论该方法准确、快速、可靠,适用于苹果中咪鲜胺及其代谢物2,4,6-三氯苯酚和氟环唑残留量的检测。     

鲫鱼体内恩诺沙星的伏安法测定

在1.0mol/LH2SO4溶液中,用碳糊电极循环伏安法和示差脉冲伏安法研究了恩诺沙星的电化学性质,并讨论了影响恩诺沙星测定的各种因素,得到了其测定的最佳实验条件。恩诺沙星的氧化峰电位是-0.10V,氧化峰电流与恩诺沙星的浓度在2.62×10-6～1.05×10-3mol/L范围内呈良好的线性关系。该测定方法的检出下限(S/N=3)为5.0×10-7mol/L。用标准加入法测定恩诺沙星平均回收率为96.5%,RSD为2.5%,恩诺沙星在-0.10V处的氧化还原为2电子、2质子参加的受扩散控制的准可逆过程。恩诺沙星的电化学测定方法用于鲫鱼样品中恩诺沙星含量的测定取得较好的结果。     

基于石墨烯构建的电化学传感器测定抗坏血酸

制备石墨烯修饰电极建立电化学方法实现对抗坏血酸的测定。采用电化学还原技术,通过一步电沉积制备石墨烯修饰玻碳电极(ERGO/GCE),并用循环伏安法研究抗坏血酸(ascorbicacid,AA)在该修饰电极上的电化学行为,结果表明,所制备的石墨烯修饰电极较裸玻碳电极对抗坏血酸有显著的电催化效果。在p H=6.5的磷酸盐缓冲溶液中,AA在-0.4 V～0.8 V扫描电位范围内有1个不可逆的氧化峰出现。在优化的实验条件下,AA的浓度在1.7×10-3 mol/L～2×10-5 mol/L范围内与其氧化峰电流值呈良好的线性关系,相关系数为0.991,最低检出限为9×10-6mol/L(S/N=3)。探究了修饰电极的稳定性、抗干扰性,结果表明电极稳定性良好,抗干扰能力较强。用此修饰电极对橙汁中的AA含量进行检测,加标回收率在97.95%～98.68%之间。用本文建立的电化学方法可用于橙汁中AA的测定,结果比较满意。     

电化学分析法同时测定植物油中的抗氧化剂TBHQ和VE

采用循环伏安法对抗氧化剂TBHQ(特丁基对苯二酚)和VE(生育酚)在有机相中的电化学氧化反应机理进行了研究,TBHQ氧化峰电位为800 mV,VE氧化峰电位为640 mV;优化了电化学法测定2种抗氧化剂的试验条件,选定有机溶剂为含6 mmol/L硫酸的1,4-二氧六环-乙腈(3∶1;V/V)溶液,支持电解质是0.03 mol/L氯化锂;在优化条件下,以微分脉冲伏安法测定TBHQ和VE的线性范围分别是4.0 ×10-5 ～5.5×10-4 mol/L和2.0×10-5 ～7.0×10-4 mol/L,检测限分别是1.5 μmol/L和1.6 μmol/L,线性系数分别是0.998和0.997.由于2种抗氧化剂的伏安波谱峰有部分重叠,常规方法难以准确其各自含量水平,因此采用偏最小二乘法(PLS)对波谱进行解析,并用该法对实际油样进行测定,回收率为97.7％～104.2％;结果表明该法在有机相中同时测定植物油中的TBHQ与VE是可行的,不需预处理,油样需要量少,方法简便快捷.     

异菌脲、咪鲜胺及其代谢物在哈密瓜贮藏保鲜中的残留动态及安全评价

目的 评价哈密瓜贮藏过程中异菌脲、咪鲜胺及其代谢物2,4,6-三氯苯酚的残留消解动态,评估其人体膳食摄入风险。方法 建立气相色谱-串联质谱法（Gas chromatography-tandem mass spectrometry,GC-MS/MS）同时测定经浸果处理的哈密瓜中异菌脲、咪鲜胺和2,4,6-三氯苯酚在冷藏和常温贮藏条件下随贮藏期延长残留量的变化,并对膳食摄入风险进行评估。结果 异菌脲、咪鲜胺在哈密瓜中的消解动态均满足一级反应动力学方程,异菌脲在常温和冷藏条件下半衰期分别为3.3、3.6 d;咪鲜胺在常温和冷藏条件下半衰期分别为3.8、4.5 d。一般人群对哈密瓜中实验农药的慢性膳食摄入的风险都较低,为可接受水平。结论 本研究通过对哈密瓜中异菌脲、咪鲜胺及其代谢物贮藏保鲜过程中残留动态的研究,为合理规范使用杀菌剂提供科学依据。     

Simultaneous Determination of Pyraclostrobin,Prochloraz, and its Metabolite in Apple and Soil Via RRLC-MS/MS

A sensitive and high-efficiency method for simultaneous detection of pyraclostrobin, prochloraz, and its metabolite in apple and soil based on QuEChERS pretreatment combined with rapid resolution liquid chromatography tandem mass spectrometry was established and validated. The limits of quantification of three compounds in two matrixes were 0.005 mg kg^?1. The average recoveries of pyraclostrobin, prochloraz, and 2,4,6-trichlorophenol in soil matrix were in the ranges of 87–105%, 86–95%, and 90–96%, respectively, with all the relative standard deviations (RSDs) of < 9.6%, while recoveries were 89–93%, 83–97%, and 89–101% in apple with the RSDs of < 6.5% at three spiking levels. For verify the applicability of this method, the real samples from three representative locations were detected. The degradation behaviors and residue distributions of pyraclostrobin and prochloraz and its metabolite in apple ecosystem were investigated. The field experiment data showed that the dissipation of pyraclostrobin and prochloraz in apple and soil followed pseudo-first-order kinetic models. The half-lives of pyraclostrobin in soil and apple were 8.6–19.8 and 7.9–15.1 days, while prochloraz were 8.9–21 and 5.8–12.4 days. The highest terminal residue of total prochloraz and pyraclostrobin in apple, after spraying three to four times with the interval of 28 days, was far below the maximum residue limits recommended by China. This research could provide guidance on a reasonable usage of prochloraz and pyraclostrobin in apple orchard.     

2,4,6-trichloroanisole in broiler house litter: A further cause of musty taint in chickens

Two unknown components in extracts of broiler house litter were identified as 2,4,6-trichloroanisole and 2,4,6-trichlorophenol; the latter compound was also found in extracts of fresh wood shavings. Experiments with pure cultures of fungi isolated from the litter demonstrated that these microorganisms were capable of methylating 2,4,6-trichlorophenol to the chloroanisole. A musty taint in broiler chickens was shown to be due to the presence of 2,4,6-trichloroanisole.     

Identification of metabolites and metabolism of hexachlorobenzene in a mold culture]

Hexachlorobenzene is but slowly metabolized by a lindane-decomposing mould culture, only pentachlorobenzene being detected as a metabolite. The degradation of pentachlorobenzene yields the following metabolites: pentachlorophenol, 2,3,4,5-tetrachlorophenol, 2,3,4,6-tetrachlorophenol, 1,2,3,4-tetrachlorobenzene, 1,2,4,5- and/or 1,2,3,5-tetrachlorobenzene, 2,3,4-trichlorophenol, 2,4,6-trichlorophenol, 3,4,5-trichlorophenol, 1,3,5-trichlorobenzene. The establishment of a degradation pattern is under way.     

Effect of relative humidity and incubation time on the O-methylation of chlorophenols in fibreboard by Paecilomyces variotii

The effect of relative humidity and incubation time on the extent of O-methylation of 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol by Paecilomyces variotii as studied ith fibreboard as the groth medium. Over a 10-eek incubation period the yields of 2,4,6-trichloroanisole and 2,3,4,6-tetrachloroanisole ere greater the higher the relative humidity; hoever, the degree of methylation of pentachlorophenol as almost negligible. At 30°C and 98% relative humidity, the methylation of the tri- and tetrachlorophenols ceased after the fourth eek; maximum chloroanisole concentrations ere observed at this time. The results indicated that methylation as the principal mechanism by hich P variotii detoxified 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol in fibreboard.     

Determination of Henry's law constants of phenols by pervaporation-flow injection analysis

A novel dynamic nonequilibrium technique for the determination of Henry's law constant (HLC) of phenols based on pervaporation-flow injection (PFI) is described. A linear relationship between HLC and the amount of phenol measured by a detector in the acceptor line of a PFI system was demonstrated. This relationship was constructed using five frequently encountered phenols (phenol, 2,4-dimethylphenol, 2,4-dichlorophenol, 2-chlorophenol, and 2,3-dimethylphenol) and used for the determination of the HLC of three other phenols (2,4,6-trichlorophenol, 2-methylphenol, and 3-methylphenol). The HLC of all eight phenols were also determined by the single equilibrium static technique (SEST). Fairly good agreementwas observed between both techniques regarding the HLC of 2,4,6-trichlorophenol, 2-methylphenol, and 3-methylphenol. On the basis of the results obtained, it was concluded that the PFI technique offers considerable advantages over SEST in terms of precision, speed, labor intensity, and possibilities for automation.