固相萃取/高效液相色谱-串联质谱法测定烟叶中春雷霉素残留量

建立了固相萃取/高效液相色谱-串联质谱(SPE/HPLC-MS/MS)测定烟叶中春雷霉素残留量的分析方法。样品经0.1%甲酸的甲醇水溶液(7∶3, v/v)超声提取后,采用混合型阳离子(PCX)小柱净化,以Kinetex PFP色谱柱分离,采用UPLC-MS/MS多反应监测(MRM)正离子模式测定,外标法定量。春雷霉素在烟叶中的最低检测浓度为0.05 mg·kg~(-1),在0.05、 0.50、 2.00 mg·kg~(-1)3个添加水平下,平均回收率为78%～87%,相对标准偏差为3%～8%。     

超高效液相色谱-电喷雾串联质谱法测定戊唑醇、肟菌酯及代谢物肟菌酸在西瓜和土壤中的残留

[目的]建立同时测定西瓜和土壤中戊唑醇、肟菌酯及代谢物肟菌酸残留量的超高效液相色谱串联质谱法(UPLC-MS/MS)。[方法]样品中的待测农药组分采用乙腈-水(体积比4∶1)提取,硅藻土液液萃取小柱净化,采用UPLC-MS/MS法,ESI(+)电离方式,多反应监测(MRM)定量测定。[结果]仪器最低检测量为戊唑醇5.0×10-13g,肟菌酯4.0×10-13g,肟菌酸2.5×10-13g;3种农药的最低检出质量分数均为0.02 mg/kg,在西瓜和土壤中的添加回收率为81.8%～94.2%,变异系数为3.67%～7.04%。[结论]该方法快速、准确、灵敏度高,适合西瓜与土壤样品中戊唑醇、肟菌酯及肟菌酸的残留量测定。     

吡噻菌胺及其代谢物在番茄中残留分析方法研究

采用QuEChERS前处理方法结合高效液相色谱-串联质谱(UPLC-MS/MS)多反应监测(MRM)模式测定吡噻菌胺及其代谢物1-甲基-3-(三氟甲基)-1H-吡唑-4-甲酰胺(PMA)在番茄中的残留量.样品经0.2％甲酸乙腈提取,N-丙基乙二胺(PSA)和无水硫酸镁净化,UPLC-MS/MS检测.方法 在0.0001～0.6 mg/L范围内有良好的线性关系,番茄中吡噻菌胺和1-甲基-3-(三氟甲基)-1H-吡唑-4-甲酰胺(PMA)最低检出量均为3×10-13 g,定量限为0.002 mg/kg.样本中添加量为0.002、0.01、0.1、1.0、2.0 mg/kg时(n=5),平均回收率92.6％～104.8％,相对标准偏差1.3％～2.7％.     

戊唑醇和肟菌酯在水稻植株、土壤和田水中的残留分析

[目的]建立同时测定水稻植株、土壤和田水中戊唑醇、肟菌酯残留量的超高效液相色谱串联质谱法(UPLC-MS/MS)。[方法]样品中的待测农药组分采用乙腈提取,过膜后直接采用UPLC-MS/MS法,ESI(+)电离方式,多反应监测(MRM)定量测定。[结果]仪器最低检测量为戊唑醇1.0×10-13 g,肟菌酯2.0×10-14 g;戊唑醇、肟菌酯在植株和土壤中最低检出质量分数均为0.01 mg/kg,在田水中均为0.001 mg/kg;在水稻植株、土壤和田水中的添加回收率为72.9%~108.5%,变异系数为2.0%~9.6%。[结论]该方法快速、准确、灵敏度高,适合稻田环境样品中戊唑醇、肟菌酯的残留量测定。     

超高效液相色谱-串联质谱法分析水稻及稻田土壤中残留的氰氟虫腙

[目的]应用超高效液相-串联质谱法(UPLC-MS/MS)建立氰氟虫腙在水稻植株、糙米及土壤中残留的分析方法。[方法]样品采用乙腈提取,乙二胺氮丙基硅烷(PSA)净化,UPLC-MS/MS检测,外标法(ESTD)定量。[结果]在0.005~1.0 mg/L质量浓度范围内,氰氟虫腙的仪器响应值与质量浓度呈良好线性关系,相关系数为0.9995,当氰氟虫腙在植株、糙米和土壤中的添加质量分数为0.005~1.0 mg/kg时,平均回收率为71.24%~93.86%,变异系数在4.0%~11.0%之间。[结论]该方法快速、灵敏,适用于检测水稻及土壤中氰氟虫腙的残留量。     

高效液相色谱法测定土壤中莠去津

采用高效液相色谱法,以乙腈+水(体积比70∶30)为流动相,使用Eclipse XDB-C_(18)液相色谱柱和DAD检测器,对土壤吸附/解吸试验中莠去津进行分离和定量分析。当添加质量分数为0.5～5.0 mg/kg时,莠去津在土壤中的回收率为92.2%～109.0%,相对标准偏差为0.04%～3.79%,莠去津在土壤中最低检测浓度为8.4×10~(-3)mg/L。该方法简单可行、准确度高,适用于土壤吸附/解吸试验中莠去津的测定。     

土壤中哒螨灵的残留分析方法研究

建立了哒螨灵在土壤中的残留分析方法。样品采用丙酮提取,二氯甲烷萃取,弗罗里硅土柱层析净化,GC-ECD检测。试验测得哒螨灵在土壤中的添加回收率为89.70%～92.90%,相对标准偏差为2.30%～4.70%,变异系数为2.09%～4.46%,方法的最低检出量为1×10-11g,检出限为5×10-3mg·kg-1。结果表明,该方法符合农药残留分析的要求。     

茶叶和茶园土壤中扑草净与莠去津残留快速测定技术

[目的]基于经典QuEChERS提取技术,采用超高效液相色谱-串联质谱(UPLC-MS/MS)检测,建立了一种同时快速测定茶叶和茶园土壤中扑草净和莠去津残留的方法。[方法]以经典QuEChERS技术为基础,分别采用不同提取剂和不同净化剂提取和净化样品,优化前处理方法,通过UPLC-MS/MS检测,建立了茶叶和茶园土壤中扑草净与莠去津残留的同时快速检测方法。[结果]茶叶样品采用乙腈提取、150 mg无水硫酸镁(AMS)+50 mg乙二胺-N-丙基硅烷(PSA)+50 mg石墨化炭黑(GCB)净化;茶园土壤采用1%甲酸-乙腈溶液(体积比)提取、150 mg AMS+50 mg C_(18)固相分散剂(C_(18))净化。在0.01~5.0 mg/L的质量浓度范围内,茶叶和茶园土壤基质中2种除草剂的质量浓度与峰面积之间具有良好的相关性,相关系数均大于0.99;在茶叶和茶园土壤中添加0.1~5.0 mg/kg的扑草净与莠去津,回收率为85.58%~106.80%,相对标准偏差为0.56%~5.59%。[结论]该方法适用于同时快速检测茶叶和茶园土壤中的扑草净和莠去津残留。     

UPLC-MS/MS法测定卡托普利及卡托普利二硫化物含量

目的:建立超高效液相色谱-串联质谱法(UPLC-MS/MS)同时测定卡托普利及其杂质卡托普利二硫化物的方法.方法:采用ACQUITY UPLC HSS T3(2.1 mm×100mm,1.8 μm)色谱柱,流动相为0.5％甲酸溶液-乙腈体积比75 ∶ 25,流速为0.5 mL·min-1,柱温40℃,进样体积5 μL....     

甜瓜、茄子及棉花3种作物叶片中呋虫胺的超高效液相-串联质谱仪检测方法

建立甜瓜、茄子及棉花3种作物叶片中呋虫胺超高效液相色谱-串联质谱仪(UPLC-MS/MS)检测方法,为研究叶片中的呋虫胺剂量分布与田间防效相关性提供方法参考。样品经乙腈提取,PSA和C_(18)净化,超高效液相色谱-串联质谱仪(UPLC-MS/MS)检测,引入基质外标法校正。在0.005～2.0 mg/L浓度范围内,呋虫胺线性关系良好。当添加质量分数为0.01～1.0 mg/kg时,呋虫胺的平均回收率为78%～99%,相对标准偏差为1.41%～7.30%。定量限LOQ为0.01 mg/kg。该方法简单快速,精确度和灵敏度高,适用于检测叶片中呋虫胺的量。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.