Magnetic molecularly imprinted polymer prepared by microwave heating for confirmatory determination of chloramphenicol in chicken feed using high-performance liquid chromatography-tandem mass spectrometry

Abstract

A magnetic molecularly imprinted polymer (MMIP) for chloramphenicol was prepared using a surface-imprinted and microwave-heating-induced polymerization method. The surfaces of the magnetic particles were first double-bond functionalized with 3-(trimethoxysilyl)propyl methacrylate (γ-MPS), followed by the copolymerization of 4-vinyl pyridine (4-VP) and trimethylolpropane trimethacrylate (TRIM) in the presence of chloramphenicol as a template and 1,1-azobis(cyclohexane-carbonitrile) (ABCN) as an initiator in a mixture of dimethyl sulfoxide and water with microwave heating at 80°C. The magnetic polymer possesses supraparamagnetic properties and was used to concentrate and cleanup chicken feed extract, followed by chromatographic separation using a Lichrospher®100 RP C8 column and detection with two multi-reaction monitoring transitions at m/z 321→ 152 and m/z 321→ 257. The mean recoveries obtained at two spiking levels were in the range of 94.6–100% The relative intra- and inter-day standard deviations were in the range of 1.4–2.6% and 5.1–5.7%, respectively. The detection limit of the method was 0.12 µg kg^?1. This confirmatory method was successfully applied to determine chloramphenicol in chicken feed samples.     

微波消解-紫外法测定水中总氮与国标方法的比较研究

将微波消解-紫外法测定总氮从方法检出限、校准曲线、精密度和准确度、实际样品测定4个方面与国标紫外法作了比较研究,进行了消解时间比对实验,说明了微波消解-紫外法测定总氮的注意事项。结果表明,微波消解-紫外法检出限为0.115 mg/L,高于国标紫外法;校准曲线具有较好线性相关系数,斜率与国标紫外法一致;方法精密性和准确性较好,实际样品测定结果与紫外法保持一致,在总氮监测中具有可行性。微波消解-紫外法节省了总氮监测的整个用时。     

微波辐射回用活性炭对水中亚甲基蓝和Cd2＋去除效果的研究

考察了微波-活性炭联合处理技术对模拟染料废水中亚甲基蓝和Cd2＋的去除效果。对于100 mL浓度为1 000 mg/L的亚甲基蓝溶液、活性炭用量为10 g时,新活性炭对亚甲基蓝的去除率为99.99%;采用700 W微波对吸附亚甲基蓝的活性炭辐射10 min进行再生并回用,经微波辐射再生10次后活性炭对亚甲基蓝的去除率为99.68%,未经微波作用反复使用10次的活性炭对亚甲基蓝的去除率为85.41%。结果表明：微波处理有效地减缓了活性炭吸附能力的下降速率,实现了活性炭再生和反复使用。在吸附过程中,Cd2＋使活性炭对亚甲基蓝的吸附能力略有下降,而共存的亚甲基蓝则促进了活性炭对Cd2＋的吸附,对新炭和再生后活性炭物理化学特性的表征证明了活性炭对亚甲基蓝的吸附为物理吸附,对Cd2＋的吸附为化学吸附。     

膨润土吸附-微波催化氧化协同处理葡萄酒废水

采用膨润土吸附-微波催化氧化技术处理葡萄酒生产废水,考察了膨润土用量、H2O2用量、微波辐照时间、微波功率、pH等5个单因素对葡萄酒生产废水处理效果的影响。确定了最终反应条件为:膨润土用量2.6 g、H2O2用量2.1mL、功率720 W、加热时间25 min、pH为3.5。在此条件下,COD去除率达到了80%以上。结果表明,该方法可快速有效地处理葡萄酒生产废水。     

微波污泥上清液为燃料的微生物燃料电池内阻分布

实验采用单室无膜悬浮阴极微生物燃料电池（MFC），考察了微波污泥上清液为燃料的MFC（MSMFC）的内阻组成。研究表明，当未投加氯化钠时，MSMFC内阻为486．13Ω。当投加100mmol／L的氯化钠时，内阻迅速下降为207．18Ω。而投加量进一步增加时，内阻变化不明显。当阳极面积从4cm2增加到8cm2时，MSMFC内阻从387．34Ω迅速下降到293．96n。而当阳极面积增加到24cm。时，MSMFC内阻变化不明显。但当阳极面积增加到60cm2时，MSMFC内阻下降了38．4％。当阴极面积从24．87cm2增加到49．74cm2时，MSMFC内阻减少了40．4％（从545．72Ω减少到220．56Q）。MSMFC中阳极内阻占主要部分，其次为阴极内阻，电解液电阻最小。随着阴阳极面积比的增加，阴阳极电阻比例减少，说明控制阴阳极面积比可以调整系统内阻的分配。     

微波加热及真空集成再生活性炭

吸附法油气回收技术中，吸附剂的再生是一个难点和研究重点。微波加热再生作为一种新技术，受到人们的广泛关注。运用正交实验，研究了微波功率、辐照时间、活性炭量和真空度对吸附了汽油油气的富活性炭的再生率和损耗率的影响，发现影响顺序为微波功率〉辐照时间〉活性炭量〉真空度。综合考虑各方面因素，得出实验的最优方案为微波功率300W、辐照时间240s、活性炭量4g、真空度O．06MPa。还研究了活性炭多次吸附一再生后平衡吸附率和表面结构的变化。结果表明，微波和真空法对活性炭的表面结构影响不大，有利于活性炭的多次循环利用。综合比较真空再生法、真空和加热再生法、微波和真空再生法的再生效果，结果表明，微波和真空再生法稳定性较好。     

Microwave assisted solvent-free synthesis and biological activities of novel imines (Schiff bases)

Twelve new ortho-Hydroxyketimines were synthesized by conventional as well as microwave method and evaluated for their antinemic activity against Meloidogyne incognita [(Kofoid and White) Chitwood]. Conventional methods for synthesis of Schiff bases require refluxing at 140°C of the reactants in different solvents for at least 24 h or more, where as the microwave-assisted synthesis has brought down the reaction time from 24 h to 1 minute. The procedure reported is simple as it does not require any organic solvents and the time has been reduced to only 1 minute. Comparative yields of all compounds by different methods revealed that the yield was low in conventional method (79–87%) as compared to microwave assisted synthesis (94–97%). The bioassay revealed that all the test compounds exhibited promising nematicidal activity; N-propyl-2-hydroxypropiophenonimine being the most effective with LC₅₀ value of 74.46 mgL^?1 followed by N-hexyl-2-hydroxyacetophenonimine with LC₅₀ value of 99.60 mgL^?1 after 72 h of exposure. The results obtained from bioassay indicated that this class of compounds has not only given a lead with regard to potential of Schiff bases in pest control, but has suggested that a carbon chain length of 6 atoms in the side chain is optimum on the basis of structure activity relationship (SAR).     

微波预处理对制革污泥絮凝脱水性能的影响

分别采用微波、絮凝剂和微波联合絮凝剂对制革污泥进行脱水预处理,考察不同处理条件下制革污泥沉降速率(SV30)、毛细吸水时间(CST)和污泥比阻(SRF)的变化,并通过粘度、水分分布和微观结构的变化探讨相关的脱水机理。结果表明,在微波输出功率为648 W、辐射时间为60 s的预处理条件下,阳离子聚丙烯酰胺(CPAM)投加剂量为8 mg/L时,污泥脱水性能达到最佳。与单独添加絮凝剂的污泥脱水相比,该条件下的SV30、CST和SRF分别降低了25.0%、48.9%和34.7%。污泥絮凝脱水前进行微波预处理能够进一步提高污泥的脱水性能,微波辐射联合CPAM进行污泥脱水时,CPAM则起主要脱水作用。微波辐射通过破坏污泥絮体结构,改变污泥中的水分分布,降低污泥的粘度,从而提高污泥的脱水性能。     

原位柱撑改性膨润土在微污染饮用水除磷中的应用研究

利用Al3+离子较易水解聚合的性质，微波辅助合成了keggin Al₁₃原位柱撑改性膨润土(PMCs)，并探究了其对微污染饮用水中磷元素的去除作用，研究表明，PMCs对磷的混凝和去除作用优于原土、工业 PAC和传统的柱撑改性膨润土(CPMCs)；影响除磷效果的主要因素有：搅拌时间、搅拌速度、水样的pH值以及初始浓度等，其最佳除磷条件是：在500 mL 10 mg/L含磷水样中加入1.5 g改性膨润土，搅拌速度为180 r/min，搅拌时间为5 h，水样pH为6～8。     

微波辅助法合成纳米ReFeO3光催化剂

以稀土金属硝酸盐La(NO₃)₃、Sm(NO₃)₃、Eu(NO₃)₃、Gd(NO₃)₃和Fe(NO₃)₃·9H₂O为原材料, 以活性炭为模板剂，聚乙烯醇(PVA)和尿素分别用作阻聚剂和均相沉淀剂，在微波辐照下制得纳米钙钛矿型化合物ReFeO₃(Re:La,Sm,Eu,Gd)。用X射线粉末衍射仪(XRD)、UV-vis漫反射仪(DRS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)对产物组成、结构、颗粒大小、形貌等进行了表征，结果表明产物均为单一钙钛矿结构的纳米颗粒。以产物为光催化剂，在可见光照射下对罗丹明B水溶液进行光催化降解实验，发现该类化合物均具有较好的光催化活性，180 min内对罗丹明B的脱色率均达到85%以上。