Fast determination of multi-mycotoxins in corn by dispersive solid-phase extraction coupled with ultra-performance liquid chromatography with tandem quadrupole time-of-flight mass spectrometry

A fast analytical method for the simultaneous determination of 9 mycotoxins, including alfatoxins （B1, B2, G1, and G2）, fumonisins （B1, B2 and B3）, zearalenone, and deoxynivalenol in corn using dispersive solid-phase extraction method and ultra-performance liquid chromatography coupled to tandem quadrupole time-of-lfight mass spectrometry （UPLC-Q-TOF-MS） was developed and validated. Samples were extracted with acetonitrile-water （84：16, v：v, containing 1% acetic acid） using ultrasonic extraction. The extracts were puriifed with a dispersive SPE method using C18 as a cleaning agent. The ifnal clear extracts were dried by nitrogen blowing and subsequently redissolved in methanol-water （5：5, v：v）. The samples were then analyzed by UPLC-Q-TOF-MS with 0.1% formic acid in ammonium acetate-methanol as mobile phase. The mean recoveries were ranged from 68.0 to 120.0%, and the relative standard deviation （RSD） ranged from 0.18 to 6.29%. Limits of detections ranged from 0.05 to 50 μg kg？1, and limits of quantiifcation ranged from 0.1 to 200 μg kg？1, which were below the legal limits set by the European Union for the legislated mycotoxins. The developed method was applied to 130 corn samples. Among the mycotoxins studied, alfatoxins B1 and fumonisins B1, B2 and B3 were the most predominant mycotoxins, and their concentrations were 0–593.12, 0–2.01×104, 0–6.94×103 and 0–3.05×103 μg kg–1, respectively.

Trace determination and characterization of ginsenosides in rat plasma through magnetic dispersive solid-phase extraction based on core-shell polydopamine-coated magnetic nanoparticles

Enrichment of trace bioactive constituents and metabolites from complex biological samples is challenging.This study presented a one-pot synthesis of magnetic polydopamine nanoparticles(Fe3O4@-SiO2@PDA NPs)with multiple recognition sites for the magnetic dispersive solid-phase extraction(MDSPE)of ginsenosides from rat plasma treated with white ginseng.The extracted ginsenosides were characterized by combining an ultra-high-performance liquid chromatography coupled to a highresolution mass spectrometry with supplemental UNIFI libraries.Response surface methodology was statistically used to optimize the extraction procedure of the ginsenosides.The reusability of Fe3O4@-SiO2@PDA NPs was also examined and the results showed that the recovery rate exceeded 80%after recycling 6 times.Furthermore,the proposed method showed greater enrichment efficiency and could rapidly determine and characterize 23 ginsenoside prototypes and metabolites from plasma.In comparison,conventional methanol method can only detect 8 ginsenosides from the same plasma samples.The proposed approach can provide methodological reference for the trace determination and characterization of different bioactive ingredients and metabolites of traditional Chinese medicines and food.

Isolation and Purification of Unstable Iridoid Glucosides from Traditional Chinese Medicine by Preparative High Performance Liquid Chromatography Coupled with Solid-phase Extraction

An efficient preparative method was successfully developed for isolation and purification of unstable components from medicinal plant extracts, using a combined method of preparative high performance liquid chro-matography(HPLC) and solid-phase extraction(SPE). The aim of this study was to obtain an effective method with high preparative efficiency and importantly to avoid the transformation of unstable compounds. The preparative HPLC system was based on an LC/MS controlled four-channel autopurification system. The SPE method was performed with a C18 packing material to trap the target compounds and to remove the acidic additive derived from the mobile phase. Using this method, the unstable iridoid glucosides(IGs) as model compounds were successfully isolated and purified from the extract of Hedyotis diffusa Willd. Six IGs(including one new minor IG) and one nucleotide compound were simultaneously obtained, each with a purity of 91% as determined by HPLC. The structures of the isolated compounds were identified by UPLC/Q-TOF MS, UV, 1D and/or 2D NMR. It was demonstrated that the combination of preparative HPLC with SPE is a versatile tool for preparative purification of unstable compounds from complex natural products.

Matrix Solid-phase Dispersion Extraction of Alkaloids from the Roots of Aconitum kusnezoffii Reichb

Matrix solid-phase dispersion（MSPD） was developed for the extraction of four alkaloids, including aconitine, mesaconitine, hypaconitine and deoxyaconitine, from the roots ofAconitum kusnezoffii Reichb. The determination of the analyte was carried out by high performance liquid chromatography with UV detection. The alkaline alumina was used as sorbent. The mixture of acetonitrile and water was used as elution solvent. Several extraction parameters, such as type of sorbent, the ratio of sample to solid support material, type of the elution solvent and the volume of the elution solvent were tested. Mean recoveries ranged from 93.16% to 102.73%, with relative standard deviations from 0.27% to 4.17%. With the extraction efficiency and time expenditure taken into account, MSPD extraction should be a comparatively good method.

PURIFICATION OF KAOLINS BY SELECTIVE DISPERSION AND FLOCCULATION

To fulfill the increasingly higher requirements on the quality of kaolins from industries, the purification of kaolins has become more and more important. Kaolins from different mines mere studied with the aitn to remove the various impurities. The mineralogical studies on the kaolins indicated that kaolinite and the major gangue minerals in the ore were all very fine. Therefore, it was difficult to separate kaolinite from the gangue minerals by conventional mineral processing techniques, such as gravity concentration, magnetic separation and flotation. Techniques for fine particles processing, i. e. selective dispersion and flocculation ivere tried to purify the kaolins. The experiments were first carried out with pure minerals of kaolinite and the gangue minerals to study the dispersion and flocculation characteristics of the different mineral suspensions under various conditions. The key factors affecting the dispersion and floccula-tion of the minerals in water were the pH of the suspension, the type and dosage of the reagents, and the strength and time of agitation. These fac-tors were adjusted to separate kaolinite from the gangue minerals. Satis-factory results were obtained with kaolin ores with different impurities from different mines. The quality of the kaolins was significantly im-proved ivith the impurities reduced to the level according ivith the specifi-cation set by the industries. The principles of the separation of kaolinite from the gangue minerals by selective dispersion and flocculation ivere dis-cussed.

Synthesis of a highly hydrophobic cyclic decapeptide by solid-phase synthesis of linear peptide and cyclization in solution

A general method was described to synthesize a highly hydrophobic cyclic peptide,cyclo[LWLWLWLWLQ]where underlines indicate D-configuration of the amino acid,by a two-step solid-phase/solution synthesis strategy.The linear decapeptide was assembled by standard Boc chemistry on solid-phase and subsequently cyclized in solution with high efficiency and reproducibility. In subsequent purification by semi-preparative HPLC,50%(v/v) DMF/H_2O was employed as the solvent to overcome the difficulty of solubilization...

分散固相萃取净化与气相色谱-串联质谱法同时测定蔬菜中157种农药残留

【目的】建立一种分散固相萃取净化结合气相色谱-串联质谱法测定蔬菜中157种农药化合物的分析方法。【方法】样品经过乙腈和QuEChERSEN-提取包提取,用无水硫酸镁150 mg、N-丙基乙二胺(primary secondary amine,PSA)75 mg、石墨化碳黑(graphitized carbon black,GCB)5 mg的填料管净化,在GC-MS/MS的动态多反应监测(dMRM)模式下检测,基质匹配标准曲线法定量分析。【结果】157种化合物在各自质量浓度范围内线性关系良好,相关系数均大于0.992 1,检出限范围为0.032~6.198μg/kg,定量限为0.107~19.496μg/kg。在0.01、0.02、0.10mg/kg加标水平下157种农药的平均回收率为74.5%~117.3%,RSD(n=6)为0.4%~10.5%。【结论】该方法前处理简单、快速、灵敏,能够满足多种农残的同时检测需求,可广泛应用于蔬菜等样品的筛查和定量检测。

Optimization and Application of Liquid Chromatography Determination of Dispersive Liquid-liquid Microextraction Purified Astaxanthin in Shrimp Waste

A new molecularly imprinted solid-phase extraction（MISPE） monolithic cartridge was synthesized, and MISPE-DLLME（DLLME=dispersive liquid-liquid microextraction） was developed for purification of astaxanthin in shrimp waste. The eluent（methanol） from MISPE was used as the dispersive solvent in subsequent DLLME for further purifying and enriching the analyte prior to high-performance liquid chromatography（HPLC） analysis. The mobile phase was methanol-acetonitrile-water-dichloromethane（85：5：5：5, volume ratio）, flow rate was 0.7 mL/min and UV wavelength was 476 nm. Under optimal conditions, good linearity was obtained in a range of 0.2--200.0 lug/mL（r2=0.9998） with a limit of detection（LOD） of 0.08 Hg/mL, and the extraction recoveries at three spiked levels ranged from 88.3%--92.5% with a relative standard deviation（RSD） less than 4.3%. Moreover, the mean contents of astaxanthin in the three batches of shrimp waste were 95.9, 85.4 and 77.2 μg/g, respectively. This method combining the advantages of MISPE and DLLME results in high selectivity and low cost, which was applied to determining the astaxanthin level in shrimp waste samples.

Development of matrix solid-phase dispersion method for the extraction of short-chain chlorinated paraffins in human placenta

Chlorinated paraffins（SCCPs） are widely used worldwide, and they can be released into the environment during their production, transport, usage and disposal, which pose potential risks for human health. In this work, an efficient, reliable and rapid pretreatment method based on matrix solid-phase dispersion（MSPD） was developed for the analysis of short-chain CPs（SCCPs） in human placenta by gas chromatograph-electron capture negative ion low-resolution mass spectrometry（GC-ECNI-LRMS） and gas chromatography–quadrupole time-of-flight mass spectrometry（GC–QTOF-HRMS）. The MSPD-relevant parameters including dispersing sorbent,sample-to-sorbent mass ratio, and elution solvent were optimized using the orthogonal test.Silica gel was found to be the optimal dispersing sorbent among the selected matrices. Under the optimal conditions, 44% acidic silica gel can be used as the co-sorbent to remove lipid and eluted by the mixture of hexane and dichloromethane（7：3, V/V）. The spiked recoveries of the optimized method were 77.4% and 91.4% for analyzing SCCPs in human placenta by GC-ECNI-LRMS and GC–QTOF-HRMS, and the corresponding relative standard deviations were10.2% and 5.6%, respectively. The method detection limit for the total SCCPs was 36.8 ng/g（dry weight, dw） and 19.2 ng/g（dw） as measured by GC-ECNI-LRMS and GC–QTOF-HRMS,respectively. The concentrations of SCCPs in four human placentas were in the range of

皮革样品中18种多氯联苯的测定——气相色谱/质谱联用法

建立了皮革样品中4-氯联苯(PCB3)、2,4-二氯联苯(PCB7)、2,2’,5-三氯联苯(PCB18)、2,4,5-三氯联苯(PCB29)、2,4’,5-三氯联苯(PCB31)、2’,3,4-三氯联苯(PCB33)、2,2’,3,5’-四氯联苯(PCB44)、2,2’,4,6-四氯联苯(PCB50)、2,3’,4’,5-四氯联苯(PCB70)、2,3,3’,4,4’-五氯联苯(PCB105)、2,3’,4,4’,5-五氯联苯(PCB118)、2,2’,3,3’,4,4’-六氯联苯(PCB128)、2,2’,3,4’,5’,6-六氯联苯(PCB149)、2,2’,4,4’,5,5’-六氯联苯(PCB153)、2,2’,3,3’,4,4’,5-七氯联苯(PCB170)、2,2’,3,4’,5,5’,6-七氯联苯(PCB187)、2,2’,3,3’,4,4’,5,6-八氯联苯(PCB195)、2,2’,3,3’,4,5,5’,6’-八氯联苯(PCB199)等18种多氯联苯的气相色谱/质谱分析方法。皮革样品用正己烷超声提取后,以弗罗里硅土(Florisil)作分散固相萃取剂净化,用气相色谱/质谱联用仪在全扫描(SCAN)-选择离子监测(SIM)模式下检测,并以2,3,4,4’,5-五氯联苯-D4(PCB114-D4)作内标,采用内标法定量。结果表明,18种多氯联苯在0.3~15μg/mL的线性良好,相关系数r≥0.9990;3个添加水平的回收率分别为84.3%~99.0%、86.4%~97.4%和86.2%~96.5%,精密度为2.9%~9.9%(n=6);检出限为0.1 mg/kg。该方法简单、有效、安全,适用于皮革样品中18种多氯联苯的同时检测。

热水浴提取结合UPLC-MS/MS同时测定枸杞中氯酸盐和高氯酸盐

该研究建立了热水浴提取-分散固相萃取(DSPE)净化-超高效液相色谱-串联质谱(UPLC-MS/MS)测定枸杞干果、鲜果中氯酸盐和高氯酸盐含量的方法。试样用7 m L超纯水在60℃水浴中振荡提取30 min后,加入13 m L甲醇涡旋5 min,离心后上清液用C18和石墨化碳黑(GCB)组合分散固相萃取净化,净化液在电喷雾负离子源和多反应监测(MRM)模式下测定,基质外标法定量。结果表明,枸杞干果、鲜果中氯酸盐和高氯酸盐均分别在1.0~100.0 ng/mL、0.5~100.0 ng/mL范围内线性关系良好,相关系数R2分别为0.998 9和0.999 2及0.998 4和0.999 0。氯酸盐检出限(LOD)为1.0μg/kg、定量限(LOQ)为10.0μg/kg;高氯酸盐LOD为0.5μg/kg、LOQ为5.0μg/kg。干果中氯酸盐和高氯酸盐平均加标回收率分别为89.9%~93.4%和76.8%~93.6%,相对标准偏差(RSD)分别小于11.0%和12.0%;鲜果中氯酸盐和高氯酸盐平均加标回收率分别为73.8%~94.9%和61.2%~90.5%,RSD分别小于11.0%和17.0%。

超声水热法制备高纯超细凹凸棒石黏土

采用分散剂协同超声水热法纯化超细化凹土,通过正交实验法考察了温度、分散剂用量、搅拌方式等因素,对超声水热法制备高纯超细凹凸棒石黏土(下称凹土)的影响;利用粒径分析、XRD和SEM等对纯化产物进行表征;得到超声水热法制备高纯超细凹土的最佳工艺条件为:加热温度40℃,六偏磷酸钠的用量是凹土用量的3%,搅拌方式是超声波+中速搅拌。在优化条件下,纯化所得凹土为疏松的白色针状晶体,粒度d90在4.7μm以下,白度达87%,纯度接近100%,且易重新分散于水中。

分散固相萃取法对鸡精中3-氯-1,2-氯丙醇的测定

A new method for determination of 3-MCPD in powder condiments was established by GC-MS method using 1,4-butanediol as an internal standard.Samples were ultrasonically extracted by ethyl acetate,and cleaned up by dispersive solid-phase extraction(d-SPE) using octadecane sorbent(C18).Then the extract was derivatized with HFBI and detected by GC-MS.The detection limitation was 1.0 μg/kg,and spiked recoveries ranged from 97%-102% with RSD of 2.1%-4.1%.

凹凸棒石黏土的提纯及其吸附性能的研究

考察了凹凸棒石黏土原矿的粒径、液固比、分散剂种类及用量对江苏盱眙凹凸棒石提纯土吸附性能的影响,并进行了激光粒度检测、X射线衍射及扫描电镜等分析。结果表明,对醇类发酵废水吸附效果最佳的凹凸棒石黏土提纯条件为:常温常压下,纯水和凹凸棒石黏土的液固比为9 m L/g,分散剂为六偏磷酸钠,用量为凹凸棒石黏土质量的4%,凹凸棒石黏土的粒度为100目。提纯过程可以有效的去除白云石和石英等杂质,提高凹凸棒石黏土的纯度;在分散剂的分散作用下,可以减小凹凸棒石黏土的粒径,使其棒晶变细变短;提纯后的凹凸棒石黏土对醇类发酵废水的吸附性能得到了明显的提高。

膜分散萃取净化湿法磷酸

采用膜分散方法研究了湿法磷酸的萃取特性,以水/磷酸/TBP+煤油为实验体系,以不同名义孔径的不锈钢纤维烧结膜为分散介质,在自制的萃取器中研究了流量、膜孔径、煤油含量、相比、磷酸浓度、萃取室体积和停留时间对单级萃取效率的影响,找出适宜操作条件。实验结果表明,流量增加,单级萃取效率呈现先增加后降低的趋势;减小膜孔名义直径,增加磷酸浓度,单级效率升高;适度增加萃取室体积,延长停留时间,对萃取有利;萃取剂中混加煤油,萃取效率下降。在分散相流量为1000 mL/min、采用10μm的不锈钢烧结膜、煤油体积分数为20%、相比1∶1、磷酸质量分数在30%～70%、萃取室体积为30 mL的情况下,单级效率可以达到96%。

破碎-絮凝法分离细长碳纳米管与碳纤维

根据碳纤维与细长碳纳米管耐磨性能与絮凝沉降性能的差异,提出了一种有效分离细长碳纳米管与碳纤维的物理方法———破碎-絮凝法.该方法包括研磨破碎、液相分散、絮凝沉降、过滤分离等步骤,可高效去除混杂于细长碳纳米管样品中的碳纤维,同时还可去除螺旋状碳纤维及细小碳颗粒等易悬浮杂质.纯化过程对细长碳纳米管无损伤.用电子显微镜和热重分析表征了纯化效果,并初步分析了纯化机理.

含硫天然气净化厂硫化氢泄漏分析及对策

以川东北某含硫天然气净化厂为对象,通过分析该净化厂的处理工艺及可能造成泄漏的各种原因,确定了硫化氢泄漏危险较高的生产单元。通过工艺压力、流量、物料组分的比对,选取了脱硫单元原料气和硫磺回收单元酸性气作为模拟泄漏物料。对该厂所在地的气象条件和厂区的地形地貌进行了调查,净化厂当地近5年风速、云量统计表明低风速和多云为主导天气,将D1.5m/s作为模拟硫化氢泄漏扩散的典型气象条件。采用了美国石油学会(API)推荐地面粗糙度长度。运用PHAST软件计算了在典型气象条件下通过3种不同孔径泄漏1 min,5min和30min,形成的立即危及生命或健康(IDLH)范围。在典型气象条件下IDLH的下风向边界距离在41m至1190m范围内,以硫磺回收单元的大孔径泄漏为最远。以小孔泄漏为例模拟并讨论了风速、大气稳定度对硫化氢扩散的影响。为降低H2S泄漏风险提出了在线监测及联锁系统设置的要求,对避免和减少硫化氢中毒伤亡事故具有指导意义。

中草药中13种代表性农药多残留的分散固相净化与气相色谱-质谱法测定

通过对QuEChERS(Quick,Easy,Cheap,Effective,Rugged and Safe)方法的改良,建立了9种中草药中13种代表性农药残留分析的气相色谱-串联质谱分析方法。新鲜样品用乙腈提取,干样品用水和乙腈提取,再加入NaCl和无水MgSO4液液分离;然后,在新鲜样品提取液中加入无水MgSO4和多壁碳纳米管,在干样品提取液中加入无水MgSO4、多壁碳纳米管和N-丙基二乙胺(Primary secondary amine,PSA),进行分散固相净化。采用气相色谱分离、选择离子监测质谱进行确证和测定,内标法定量。3个添加水平(0.02～0.4 mg/kg)的平均回收率为67.9%～100.3%,相对标准偏差为0.6%～11.0%;方法定量限(LOQ)在0.004～0.03 mg/kg之间;检出限(LOD)在0.009～0.01 mg/kg之间。采用本方法检测12例市场样品,其中3例样品检测出目标农药。

倾斜晶析塔内有机物纯化过程的理论与实验研究

使用低共熔型对、邻二氯苯体系，研究全回流稳态操作条件下倾斜晶析塔内有机物的纯化过程，基于发汗机理建立了倾斜晶析塔提纯段的轴向扩散模型。研究结果表明，倾斜晶析塔对有机物提纯有很好的适应性，在进料浓度为62％～85％、搅拌速率为5～10r／min范围内，产品纯度均可达到99．9％，轴向扩散模型能很好地描述稳态操作时塔内的浓度分布规律。

碳纳米管在乙二醇水溶液中的分散性

采用硫酸和硝酸混合酸对催化裂解法(CVD法)制备的多壁碳纳米管(CNTs)进行纯化,以超声仪为分散设备,分别研究了在乙二醇水溶液中加入不同类型的阳离子、阴离子、非离子型等表面活性剂对碳纳米管分散性的影响,通过记录碳纳米管悬浮液的稳定保存时间观察其分散性.结果表明:十六烷基三甲基溴化铵和乳化剂OP作为分散剂的分散效果最好.