碲化镓纳米片中单斜晶相和六方晶相共存的光谱特征（英文）

快速发展的二维层状材料为构建新型高效的微纳发光器件和光电探测器件提供了新的平台.其中碲化镓纳米片备受关注,这是因为碲化镓从少层到块体都具有极强的发光性能,因而可以降低二维微纳器件的制备条件.然而碲化镓纳米片具有单斜和六方等多种晶相,使其发光特性和光谱结构异常复杂,目前还缺少对不同厚度碲化镓纳米片荧光光谱的系统研究.本文研究了不同厚度碲化镓纳米片的荧光光谱和拉曼光谱,以及荧光光谱从低温(4 K)到室温的演化行为.通过光谱分析,发现单斜晶相和六方晶相可能同时共存于多层碲化镓纳米片中.为了阐述相关实验结果,构建了如下原子结构模型:其中六方晶相位于纳米片的顶层与底层,而单斜晶相位于纳米片的中间位置.基于温度依赖的荧光光谱,可以获得六方晶相的光学带隙为1.849 eV,且该激子峰只能在较高温度(>200 K)下和声子辅助下才能表现出显著的荧光发射行为.进一步的实验结果确定了六方晶相的激子-声子相互作用强度约为1.24 meV/K.本工作证实了碲化镓纳米片中单斜晶相与六方晶相共存的实验现象,为研究碲化镓纳米片的晶相变化和激子动力学,以及探究碲化镓的奇异物理化学特性,提供了新的见解.     

注射泵辅助微固相萃取-气相色谱-串联质谱法检测大米中有机磷类农药残留

采用水热法一步合成了氨基官能化MIL-101(Cr)金属骨架材料,将其作为注射泵辅助微固相萃取吸附剂,结合气相色谱-串联质谱检测,建立了稻米中6种有机磷农药的快速分离分析新方法。对前处理过程的条件进行优化,得到最优条件：材料用量5 mg、上样溶液pH=7.0,上样溶液盐浓度为5%NaCl,解吸溶剂丙酮的解吸体积为5 mL,最佳解吸速率0.7 mL/min。在最优条件下,6种有机磷农药在空白稻米样品中低中高三种添加浓度的回收率在83.0%～113.3%之间,日内日间相对标准偏差小于12.5%,表明所建立的方法具有良好的准确度和精密度。最后,将所建立的方法用于实际稻米样品中有机磷农药残留的分析,取得了很好的效果。     

基于甲基苯丙胺和吗啡的胶体金免疫层析试剂盒检测法的可靠性评价

通过固相萃取-液相色谱-多级质谱(SPE-LC-MS/MS)联用技术和毒品胶体金免疫层析试剂盒检测法对13种中药及调味品样品中甲基苯丙胺及吗啡分别进行定量分析,依据LC-MS/MS检测结果,对毒品胶体金免疫层析试剂盒检测法进行可靠性评价。实验结果表明:型号1试剂盒对甲基苯丙胺和吗啡的特异性均不高,检测准确率分别为57.7%与78.8%;型号2试剂盒对甲基苯丙胺的特异性不足,准确率为73.1%,但对吗啡的检测准确率达到100%。在利用毒品胶体金免疫层析试剂盒进行毒品快速筛查时,应注重排除干扰因素以提高免疫胶体金层析试剂盒的检测准确度。     

固相萃取净化-气相色谱法测定食用菌及其栽培基质中26种多溴联苯醚

建立了食用菌及其栽培基质中26种多溴联苯醚（PBDEs）的检测方法。考察了不同提取溶剂,不同净化材料,不同仪器条件对检测结果的影响,确立了乙腈提取,盐析分层,乙二胺-N-丙基硅烷（PSA）复合去活化硅胶固相萃取柱净化,气相色谱-电子捕获器（GC-ECD）分析,外标法定量的检测方法。方法的线性相关系数大于0.996,检出限为0.02～0.06μg/kg,定量限为0.06～0.2μg/kg,方法加标回收率在72.5%～119.2%之间,相对标准偏差在2.2%～14%之间。     

聚吡咯纳米纤维固相萃取-气相色谱法测定小鼠粪便中短链脂肪酸

建立了一种96微孔板装填聚吡咯纳米纤维固相萃取小鼠粪便中的短链脂肪酸的气相色谱测定法,解决了因采用水基质提取短链脂肪酸后直接进样分析而导致的气相色谱柱使用寿命缩短的问题。采用静电纺丝技术及原位化学聚合法制备聚吡咯纳米纤维,将其装填入96微孔板插管,提取小鼠粪便样本中的短链脂肪酸,有机相洗脱后采用气相色谱法测定样本中的短链脂肪酸含量。结果表明,6种短链脂肪酸在10～500μg/mL范围内线性关系良好,加标回收率在92.5%～128.3%之间。采用聚吡咯纳米纤维固相萃取,可有效提取粪便样本中的短链脂肪酸成分,并将水基质样本转换为有机相基质,有利于目标物信号检出,延长气相色谱柱的使用寿命。     

固相萃取净化结合液相色谱-串联质谱法测定禽蛋中5种阿维菌素类化合物

建立了同时测定禽蛋中（鸡蛋、鸭蛋和鹅蛋）阿维菌素、伊维菌素、多拉菌素、乙酰氨基阿维菌素、莫西菌素等药物残留的液相色谱-串联质谱法（LC-MS/MS）。禽蛋样品采用1%甲酸乙腈溶液提取并盐析分层,上清液经Oasis PRiME HLB小柱净化。以0.1%甲酸乙腈溶液和含10 mmol/L乙酸铵的0.1%甲酸水溶液为流动相,采用ACQUITY UPLC BEH C₁₈色谱柱进行分离,质谱法在正离子模式下检测,外标法定量。结果表明5种目标物在0.1～250μg/L范围内呈现良好的线性,相关系数（R²）>0.99。莫西菌素在禽蛋中的定量限（LOQ）为1.0μg/kg,其他药物定量限为0.5μg/kg,回收率79%～108%,相对标准偏差（RSD）为1.2%～9.3%。同时发现,质谱气帘气压力是影响阿维菌素类药物灵敏度的关键因素。该方法能够满足禽蛋中5种阿维菌素类药物同时检测的要求。     

气相色谱–串联质谱法测定中药材中35种农药残留的样品处理方法

分析对比气相色谱–串联质谱(GC–MS/MS)法测定中药材中35种农药残留的3种样品处理方法,为中药材中农药残留检测提供参考.以乙腈为提取溶剂,样品经高速匀浆提取后,取提取液进行净化处理.比较了基于QuEChERS原则的处理方法、石墨化碳黑–氨基复合固相萃取(GCB–NH2)法和亲水亲油平衡材料固相萃取(HLB)法3种...     

过渡金属磷化物纳米材料催化尿素电解制氢研究进展

电解水制氢技术操作简单、产物纯度高,是一种前景广阔的绿色制氢方式.然而,阳极析氧反应(OER)具有较高的热力学电势和缓慢的动力学,严重阻碍了电解水制氢技术的大规模工业应用.近年来,人们发现利用较低热力学电势的尿素氧化反应(UOR)取代阳极OER能够同时实现氢气的节能生产和尿素废水的净化.但这种技术的挑战在于尿素电解过程...     

基于混酸回流制备碳点的中和过程

Carbon dots (C dots) are relatively novel carbon nanomaterials that have attracted significant interest due to their unique photoluminescence, good biocompatibility, and stability. The preparation methods of C dots was usually summarized into "top-down" and "bottom-up", and mixed acid reflux is a top-down strategy that can be used to synthesize C dots, during which neutralization is a necessary step that can significantly influence the properties and potential applications of the final product. Previously, this research area mainly focused on tuning the properties of C dots by changing the starting materials and/or varying the reaction conditions; the influence of the reagents used during neutralization has been largely ignored. As the previously reported C dots prepared by mixed acid reflux were obtained from different starting materials under varied conditions, a meaningful comparison is difficult. Herein, yellow-emitting C dots were prepared by mixed acid-refluxing a carbon-rich material derived from fullerene carbon soot. For the same batch of as-prepared C dots, the influences of four reagents, i.e., NaOH, Na₂CO₃, K₂CO₃, and NH₃·H₂O, during neutralization on the structures and photoluminescence of the resulting C dots were investigated in detail. The results of thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy clearly showed that the reagent used during neutralization can affect the degree of dissociation of the acidic functional groups on the C dots. This is further supported by examination of the C dot/surfactant mixtures where subtle changes in the phase behavior were observed. Structural changes of the C dots cause variations in their surface states, ultimately altering the optical characteristics, including UV-vis absorption and fluorescence. Among the treated C dots, the sample prepared with Na₂CO₃ showed the strongest emission under the same excitation wavelength, while that prepared with NH₃·H₂O exhibited a distinct red shift (~8 nm) in the emission curve. The results presented herein provide clear evidence that neutralization reagent selection is important for optimizing the properties of the resulting C dots obtained by mixed acid reflux. In addition, the photoluminescence of the C dots can be influenced by their counterions, providing a novel method for tuning the properties of C dots while explaining their behavior in saline solutions. In short, the basicity of the neutralizing reagent and the type of counterions affect the structure of the C dots surface, which brings different performances. This work reminds researchers that it is necessary to use the type of neutralizing reagent as an experimental condition when preparing C dots in the future.     

基于混合吸附剂磁性固相萃取/高效液相色谱-串联质谱法测定水中磺胺和喹诺酮类抗生素残留

通过制备磁性大孔有机共聚物材料(Fe₃O₄@Si O₂@PLS)和磁性金属有机骨架材料(Fe₃O₄@ZIF-8),将两种材料同时作为磁性吸附剂,建立了混合吸附剂磁性固相萃取/高效液相色谱-串联质谱(MSPE/HPLC-MS/MS)测定水中4种磺胺类和8种喹诺酮类抗生素残留的分析方法。通过扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)和X-射线衍射仪(XRD)对两种磁性材料进行表面形貌和结构表征,结果显示,亲水亲脂大孔有机共聚物(PLS)包覆于磁性纳米粒子Fe₃O₄表面,且Fe₃O₄成功附着于正六边形金属有机骨架材料(ZIF-8)晶体表面,可以满足磁性固相萃取的要求。通过优化吸附剂用量、萃取方式、吸附时间、样品p H值、洗脱剂种类及洗脱时间,在最优的实验条件下,12种目标物的线性范围为0.5～10μg/L,相关系数(r²)为0.996 1～0.999 8,检出...