C18键合硅胶柱富集/AAS法测定水体中痕量锰的研究

对水体中痕量锰的C18键合硅胶富集／AAS法进行了研究。重点讨论了该法测定的一些影响因素及最佳条件。结果表明,常温下对于10^-6mol／L浓度的锰,pH5．50～6．50范围内,螯合剂用量在0．20～0．40mL范围内时,测定结果最佳;且酒石酸、HA、柠檬酸、葡萄糖的质量浓度达1．00mg／L时对测定无影响。该法测定水中锰离子的浓度,检出限为0．03umol／L(3σ),在0．50～5．00umol／L范围内,具有很好的线性关系。     

亲水改性C18填料的制备及其在萃取水中酚类化合物中的应用

通过在甲基丙烯酸十八酯(SMA)中加入亲水性单体甲氧基聚乙二醇甲基丙烯酸酯(PEGMEA),以1-正丙醇/1,4-丁二醇为致孔剂,热聚合得到具有一定亲水性的新型C18填料,并将该填料应用于固相萃取(SPE)富集水中的酚类化合物。实验优化了致孔剂的配比、SPE过程中上样溶液pH值、洗脱剂种类等参数。在上样溶液pH为6.0,以5.0 mL乙腈为洗脱剂的优化条件下,5种酚类化合物在0.5～10 mg/L范围内呈良好的线性关系,检出限为0.16～0.47 mg/L。所制备的亲水改性C18材料已成功用于大辽河水样中酚的检测,平均加标回收率为64.33%～92.14%, 相对标准偏差为4.2%～6.4%(n=3),证明了该填料对环境水样中痕量酚类化合物富集的可靠性。     

亲水相互作用色谱柱串联C18柱高效分析饮品中的胭脂红

建立了亲水相互作用色谱柱(HILIC)串联C18柱的方法,高效分离实际样品中的胭脂红,并对色谱柱的串联顺序以及色谱分离条件进行优化。结果表明:当HILIC柱在前C18柱在后,流动相为乙腈-乙酸铵(5 mmol/L)=91∶9(V/V),流速为0.9 mL/min,柱温为25℃,检测波长为508 nm时,此时胭脂红的分离效果最佳。在最佳的色谱分离条件下,选用两种市售饮品进行实际样品的测定,回收率在81.2%~119%。方法适用于水相样品中的强极性物质的高效分离与分析。     

毛细管区带电泳的离子交换在柱预富集技术研究

提出了离子交换固相萃取的毛细管区带电泳在柱预富集技术。预富集毛细管和分离毛细管的端面靠紧,二者通过一段带侧孔的聚四氟乙烯（PTFE）套管固定。预富集毛细管内壁键合羧基阳离子交换基团,进样时分析离子被保留在预富集管的固定相上,用2mol／L的氯化铵溶液洗脱,再进行毛细管区带电泳分离。方法成功富集和分离了两种低浓度的药物阳离子,普萘洛尔和美托洛尔的灵敏度比常规电动进样分别提高4200和3400倍,其浓度检出限分别为0．02μg/L和0．14μg/L。     

C18-MCM-41新型涂层在固相微萃取中的应用

固相微萃取（SPME）是集采样、萃取和富集于一体的样品前处理技术,该技术于1990年由Pawliszyn提出。由于其不使用有机溶剂,且简便、快速、样品用量少,因而,倍受分析工作者的青睐。     

水中农药多效唑的新型相膜微萃取富集测定

利用C18固相萃取膜和小玻璃磁子自制固相膜微萃取搅拌棒,首次建立了测定小体积水样中农药残留的样品处理技术.优化了萃取和解析条件,最佳条件:样品体积35 mL;萃取温度30℃;搅拌速率900 r/min;萃取时间和解析时间均为120 min,解析溶剂为甲醇,体积0.45 mL.方法的检出限为0.8μg/L(S/N=3).检验了该方法的准确度和精密度(RSD小于5%).在此条件下测定了黄河水中多效唑的含量,结果证明黄河水中该物质的残余量在检出限以下.     

高效液相色谱法（C18柱）测定富马酸克敏停片的含量

富马酸克敏停(Clemastine Fumarate)为一新型抗组胺药,并为美国药典二十一版收载,其含量测定采用HPLC法,柱填料为辛烷基键合硅胶。1981年,Gvebitz等采用荧光衍生HPLC法测定富马酸克敏停的含量,但用十八烷基键合硅胶柱分析富马酸克敏停片未见报道。本文采用国内较为普遍使用的十八烷基键合硅胶柱,用HPLC法对富马酸克敏停片的含量进行了测定,方法较简便,具有流量低、灵敏度较高等优点。 实验部分 (一)仪器Varian 5800型高效液相色谱仪,DS-600数据处理机。 (二)试剂 甲醇、磷酸二氢钾、磷酸氢二钾均为分析纯。对照品及样品均为本所提供。 (三)色谱条件 色谱柱:Micropak SP-C_(13)柱(150×4mm),流量:1.5ml/min,柱温:35℃,进样量:20μl定量环,流动相:甲醇/pH7.8磷酸缓冲液(93/7,V/V),用UV-200可调波长紫外检测器     

n-InP在Fe3+/Fe2+溶液中复阻抗的计算机拟合分析

本文测定了不同电位及不同光强下, n-InP在Fe~(3+)/Fe~(2+)溶液中的复阻抗图, 从一个等放电路用计算机对结果进行了拟合, 并对拟合结果进行了讨论。     

C18固相萃取圆盘与聚氨酯泡沫(PUF)萃取水体中二噁英的对比性研究

水体样品经玻璃纤维膜过滤富集颗粒物后使用C18膜或聚氨酯泡沫固相萃取水相中二噁英,冷冻干燥后索氏抽提,抽提液依次经多段混合硅胶柱、氧化铝柱净化后,采用13C同位素稀释法对其中的17个2,3,7,8-氯取代二噁英(PCDD/Fs)同系物进行测定.研究结果表明,用该法分析二噁英标准溶液、C18膜或聚氨酯泡沫各4次,分析结果的平均值和标准偏差都符合EPA1613规定值,回收率分别为74%～130%和61%～110%;标准参考样的分析结果(n=3)符合标准参考值范围.实验表明在大水量(大于100 L)样品前处理阶段使用聚氨酯泡沫替代C18膜是合理、可行的.     

GC-MS法测定植物提取物中19种邻苯二甲酸酯类化合物

建立了植物提取物中19种邻苯二甲酸酯类化合物(PAEs)的气相色谱-质谱(GC-MS)分析方法。样品经水溶解,正己烷提取,弗罗里硅土小柱净化,采用GC-MS法在选择离子监测模式(SIM)下进行测定。结果表明:方法在0.1～10 mg/kg范围内具有良好的线性关系,相关系数均大于0.999,检测限为0.14～1.2μg/kg,加标回收率为62.1%～118.2%,相对标准偏差为0.61%～13%。方法可满足植物提取物中PAEs的定性和定量测定。     

17种酞酸酯类环境激素GC-EI-MS分析方法的建立

以17种酞酸酯类(Phthalic Acid Esters,PAEs)环境激素为目标物,选择苯甲酸苄基酯为内标物,优化了气相色谱的升温程序和质谱的离子化方式等分析条件,初步解析了PAEs和内标物的电子轰击离子源-质谱谱图,并确定了选择离子检测方式的特征碎片离子,建立了同时分析17种PAEs环境激素的GC-EI-MS SIM分析方法,并应用于水生植物海白菜样品的分析。     

Structure of 〔Na(DB18C6) (CH_3OH)〕_2W_6O_(19)·(DB18C6)·(CH_3OH)

1INrnODUCTIoNlnthepreviouspapers,wehavereportedthesynthesisandcrystalstructureofseveralcrownetherpolyoxometalates"-",nowwestudythestructureofthetitlecomplexandcompareitwithsomeothercrownetherpolyoxometalatecomplexes.2EXPERmENTALToal5OmLaqueoussolutioncontaining32g(1OOmol)Na,WO#.2H,Opre-justedtopH=3.5withchloricacid,14g(4Ommol)(n-Bu)'NBrwasadded,thenwhitepowderwasformed.ThewhiteprecipitateobtainedwithafiltrationwaskeptasthenewmaterialAinnextstep.AmixtureoflgAandO.3g(O.8mmol)DB18…     

C_(18)膜萃取/液相色谱-质谱联用法测定极地水体中有机磷酸酯

建立了C_(18)膜萃取/液相色谱-质谱联用技术测定极地水体中10种有机磷酸酯(OPEs)的方法。根据优化后的样品前处理及仪器方法,利用C_(18)膜富集4 L水体中的10种OPEs,经二氯甲烷超声提取,在电喷雾正离子模式下,采用选择反应监测(SRM)模式进行分析,线性相关系数为0.994 4~0.999 9。10种OPEs的加标回收率为64.1%~115%,方法检出限为0.08~0.55 ng/L。该方法适用于极地水体中10种OPEs的分析,利用该方法对北极水体样品中的10种OPEs进行检测,测得冰川融水中∑OPEs的质量浓度为0.64~6.64 ng/L,海水中∑OPEs的质量浓度为0.09~2.03 ng/L。     

Evaluation of the Removal of Selected Phthalic Acid Esters (PAEs) in Municipal Wastewater Treatment Plants Supported by Constructed Wetlands

Phthalic acid esters (PAEs) have a negative impact on living organisms in the environment, therefore, are among the group of Endocrine Disrupting Compounds (ECDs). Unfortunately, conventional methods used in municipal wastewater treatment plants (MWWTPs) are not designed to eliminate PAEs. For this reason, the development of cheap and simple but very effective techniques for the removal of such residues from wastewater is crucial. The main aim of this study was the evaluation of the removal of six selected PAEs: diethyl phthalate (DEP), di-n-octyl phthalate (DOP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), bis(2-ethylhexyl) phthalate (DEHP) and dimethyl phthalate (DMP), in real MWWTPs supported by constructed wetlands (MWWTP–CW system). For the first time, the possibility of using three new plants for this purpose, Cyperus papyrus (papyrus), Lysimachia nemorum (yellow pimpernel) and Euonymus europaeus (European spindle), has been presented. For determining the target PAEs in wastewater samples, a method of SPE (Solid-Phase Extraction)–GC–MS(SIM) was developed and validated, and for plant materials, a method of UAE (Ultrasound-Assisted Extraction)–SPE–GC–MS(SIM) was proposed. The obtained data showed that the application of the MWWTP–CW system allows a significant increase in the removal of DEP, DBP, BBP and DEHP from the wastewater stream. Euonymus europaeus was the most effective among the tested plant species for the uptake of analytes (8938 ng × g⁻¹ dry weight), thus, this plant was found to be optimal for supporting conventional MWWTPs.     

Multi-walled carbon nanotubes modified with iron oxide and silver nanoparticles (MWCNT-Fe3O4/Ag) as a novel adsorbent for determining PAEs in carbonated soft drinks using magnetic SPE-GC/MS method

The synthesis of compounds with an excellent adsorption capability plays an essential role to remove contaminants such as phthalic acid esters (PAEs) with potential carcinogenic characteristics from different food products. In this context, for the first time, a novel adsorbent (MWCNT-Fe₃O₄/Ag) was synthesized by using iron (magnetic agent), and silver (catalytic and surface enhancer agent) to further approach in a magnetic SPE-GC/MS method for determining of PAEs in carbonated soft drink samples. The limit of detection (LOD) and limit of quantification (LOQ) values of MSPE-GC/MS were determined in six PAEs as a range of 10.8–22.5 and 36–75 ng/L, respectively. Also, the calibration curves of PAEs were linear (R₂ = 0.9981–0.9995) over the concentration level of 10.000 ng/L and the recoveries of the six PAEs were ranging from 96.60% to 109.22% with the RSDs less than 8%. Moreover, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and transmission electron microscopy analyses (TEM) were utilized to characterize the produced MWCNT-Fe₃O₄/Ag. Based on the findings, the surface of MWCNT is relatively uniform, which became coarser after loading with Fe₃O₄/Ag particles. Also, EDX spectrum showed the carbon (C), iron (Fe), oxygen (O), Ag and copper (Cu) are the main components of synthesized MWCNTs-Fe₃O₄/Ag. The successful adhesion of Fe₃O₄/Ag on the texture of MWCNTs using a co-precipitation method was confirmed by XRD and FT-IR assays. Additionally, excellent crystallinity and clear lattice nanocrystals fringes of prepared MWCNT-Fe₃O₄/Ag was demonstrated by TEM analysis. Based on the obtained VSM images, the prepared sorbent (MWCNT-Fe₃O₄/Ag) has the good magnetic performance for magnetic separation and extraction processes. It was concluded that the synthesized MWCNT-Fe₃O₄/Ag could be used as an efficient adsorbent for determining contaminants such as PAEs in different beverage samples.     

A Comparative Study of Homemade C18 and Commercial C18 Sorbents for Preconcentration of Lead by Minicolumn Solid Phase Extraction

A comparative study of commercial C₁₈ chemically immobilized on silica and homemade C₁₈, as sorbents for Pb complexed with O,O-diethyl-dithiophosphate (DDTP) in a flow injection preconcentration system is reported. The homemade C₁₈ sorbent was obtained by sorption of poly(methyloctadecylsiloxane) (PMODS) on the silica support followed by immobilization using thermal treatment. The method follows the concept of green chemistry, since there are no toxic residues after synthesis. The complexed Pb was formed in 1.0molL^–1 HCl medium and retained on the minicolumn filled with the sorbents. The elution was carried out using ethanol, and the richest 210µL fraction was collected and analyzed by flame atomic absorption spectrometry. Chemical and flow variables were optimized for each sorbent. The results demonstrated that the performance of the proposed homemade C₁₈ sorbent for preconcentration of Pb complexed with DDTP is very similar to commercial C₁₈ chemically bonded on silica. By processing 25mL, the enrichment factors were 129 and 125 for commercial C₁₈ and homemade C₁₈, respectively. The limit of detection for commercial and homemade C₁₈ was 0.2µgL^–1 and 0.6µgL^–1, respectively. The relative standard deviation (RSD) was lower than 1.2% for both sorbents for a Pb concentration of 100µgL^–1. The method was also applied successfully to the analysis of water samples, and the accuracy was tested by recovery measurements on spiked samples and biological reference material.     

The negative differential resistance mechanism of a molecular device based on double‐cage fluorinated fullerene C20F18(NH)2C20F18: A theoretical study

The electronic transport properties of the molecular device based on double‐cage fluorinated fullerene C₂₀F₁₈(NH)₂C₂₀F₁₈ were studied theoretically. The results show that the device exhibits two negative differential resistance (NDR) peaks in its I‐V curve. The NDR peak under low bias voltage originates from the bias‐induced alignment of the molecular orbitals, and the conduction channel being suppressed at a certain bias voltage is the main reason for the NDR peak under a relatively high bias voltage.     

Metal Cation Transport Studies Comparing Dibenzo-18-crown-6 (DB18C6) with N,N,N′,N′-Tetrakis (n-propyl)-2,3- naphthalenedioxydiacetamide (NPr)

The previously synthesized3,6-dioxa-4,5-disubstitutedoctanedicarboxamides including NPr bind cationsin methanol in the order: Ca²⁺ > Sr²⁺ >Ba²⁺ > Mg²⁺ > Na⁺,K⁺. These compounds also extract Group II cations better thanGroup I cations from water to dichloromethane. In contrast, thesediacetamides were found by W. Simon et al., to sense Na⁺ >Ca²⁺ when they were incorporated into ion-selective electrodesusing a low dielectric constant solvent. It was of interest to determine theorder of Group I and Group II cation transport rates of these compoundsusing a three-phase system with a liquid organic phase of low dielectricconstant. We now report that NPr transports thiocyanates in such a systemusing dichloromethane in the order K⁺ (7.2) >Ca²⁺ (6.6) > Ba²⁺ (5.8) > Na⁺(1). The transport rate for KSCN with DB18C6 is 20.5 times faster than withNPr.