固相萃取-超高效液相色谱法测定化妆品中6种硝基酚

建立了同时测定化妆品中6种硝基酚的固相萃取-超高效液相色谱分析方法。样品采用乙腈为提取溶剂,经超声提取后再做高速离心处理;上清液以Oasis HLB固相萃取柱净化,收集甲醇洗脱液,采用色谱分析。液相色谱分析方法:选择全氟苯基色谱柱,以乙腈和乙酸铵及0.1%甲酸作为流动相,梯度洗脱,检测波长为220nm,在优化的固相萃取前处理和液相色谱分离分析条件下,净化效果满足要求。6种硝基酚类化合物在20min内实现完全基线分离,检出限为0.02~0.04mg/L,回收率为86.3%~103.6%,相对标准偏差为3.4%~7.1%。本方法准确、快速、灵敏度高,可用于化妆品的实际检验。     

气相色谱-质谱法测定洋葱中129种农药残留

建立了组合柱固相萃取-气相色谱-质谱法快速测定洋葱中129种农药残留的分析方法。样品用乙腈均质提取,盐析分配,提取液经C18和PSA组合柱固相萃取净化后供气相色谱-质谱仪(GC-MS)分析。采用选择离子扫描方式,外标法定量。该方法简便、快速,通过优化前处理和上机条件,在最优条件下进行测试,方法的定量下限(S/N≥10)为0.01~0.1 mg/kg,在加标水平为0.1 mg/kg时,方法回收率为63.2%~113.1%,相对标准偏差为5.3%~14.4%。     

食品红色着色剂中工业染料直接桃红的检测方法研究

本文建立了食用色素中直接桃红的高效液相色谱-二极管阵列检测方法。样品经纯水提取、离心和过滤后,依次通过C18固相萃取小柱和自制聚酰胺固相萃取小柱净化富集,浓缩后经高效液相色谱分离检测。该方法对不同色素产品中直接桃红的检测限为1-200mg/kg;定量限为3-700mg/kg;色素空白样品加标回收率为64.8%～106.3%,相对标准偏差(RSD)为2.4%～11.1%(n=3),直接桃红染料在0.050～2mg/mL浓度范围内呈良好的线性关系,线性回归系数r均大于0.999。     

固相萃取-气相色谱-质谱联用法检测进出口蔬菜产品中百菌清残留

建立了固相萃取-气相色谱-质谱法检测蔬菜中百菌清残留的分析方法。样品用乙腈-水-磷酸混合液提取,经液液分配、Florisil/Na2SO4柱净化后过滤膜上机。采用选择离子扫描方式,外标法定量。通过优化前处理和上机条件,在最优条件下进行测试,实验结果百菌清的定量检出限为0.001mg/kg,在加标水平0.005～0.1mg/kg范围内,回收率为78.65%～90.67%,相对标准偏差为3.5%～5.8%。该方法简便、快速、净化效果理想,能满足残留分析的要求,可用于进出口蔬菜中百菌清残留的检测。     

SPE-GC/MS法测定水中有机磷和氨基甲酸酯农药

采用固相萃取(SPE)技术,对水样中20种有机磷类、氨基甲酸酯类农药进行提取、净化、浓缩前处理,优选了固相萃取小柱填料及萃取、净化条件.优化了气相色谱,质谱(GC/MS)仪器工作参数,建立了水样中20种农药的SPE-GC/MS分析方法.针对不同农药,本法回收率在90.83%～105.0%之间,测定精密度BSD在3.20%.12.52%之间.SCAN检测模式的检出限在0.0003mg/L～0.003mg/L之间,SIM检测模式的检出限在0.0002mg/L～0.0022mg/L之间.本法简便、快速、灵敏、可靠性强.     

茶叶中啶虫脒残留量气相色谱分析方法研究

本文对茶叶中啶虫脒残留量的气相色谱分析方法进行了研究。方法:样品用乙腈提取后,采用活性碳固相萃取柱和弗罗里硅土固相萃取柱净化,采用电子捕获检测(ECD)的气相色谱仪测定。该方法检测底限为0.01 mg/kg,当样品添加浓度在0.05mg/kg-0.20mg/kg范围内,添加回收率在82.4%-100.7%,相对偏差为5.5%-7.7%。     

简论农药残留量检测中的样品前处理技术

简要介绍了农药残留量测定中样品的提取、净化等前处理技术最新研究进展 ,包括固相萃取、固相微萃取、超临界流体萃取、微波辅助提取、免疫亲和色谱和凝胶色谱等技术     

UPLC-MS-MS法测定鳗鱼中孔雀石绿、结晶紫及其代谢产物的残留

本研究探索了用超高效液相色谱串联质谱法同时测定鳗鱼样品中孔雀石绿、结晶紫及其代谢物无色孔雀石绿和无色结晶紫的残留量。使用快速检测试剂盒提取鳗鱼样品,经专用柱进行固相萃取净化后,再采用UPLC-MS-MS法同时测定样品中孔雀石绿、无色孔雀石绿、结晶紫和无色结晶紫。结果发现,在0.5μg/kg的加标条件下,孔雀石绿、无色孔雀石绿、结晶紫和无色结晶紫的回收率分别为123.7%、109.6%、126.4%、106.2%。该方法前处理快速、高效,检测快速、准确、灵敏,符合水产品食品企业对样品的检测需求。     

高效液相色谱测定燃香中丙烯酰胺的研究

建立了固相萃取高效液相色谱测定燃香中丙烯酰胺含量的方法。色谱条件:流动相为乙腈-水(20∶80,V/V),检测波长为198nm,流速为0. 8mL/min。用超纯水提取燃香样品中的丙烯酰胺,提取液经ACA固相萃取柱净化浓缩,外标法定量。结果表明:丙烯酰胺在10～100mg/L范围内均线性良好,相关系数大于0. 999,方法检出限为3mg/kg,加标回收率在96. 6～98. 0%之间,相对标准偏差为0. 049%。     

气相色谱脉冲火焰光度法快速测定茶叶中12种有机磷农药残留

本文建立了超声提取,固相萃取小柱净化,GC-PFPD快速测定茶叶中12种有机磷农药残留的分析方法,重点考察并优化了茶叶中有机磷农药的提取与净化。样品经丙酮提取,PSA/活性炭固相萃取柱净化,以乙腈/甲苯混合溶液洗脱。实验结果表明各组分在0.05μg/mL～1.0μg/mL浓度范围均具有良好的线性关系,相关系数r均大于0.99,样品回收率在92.5%～109.5%之间,相对标准偏差小于11.0%,12种有机磷农药的检出限在0.005mg/kg～0.01mg/kg。     

Determination of clenbuterol in bovine liver by combining matrix solid-phase dispersion and molecular imprinted solid-phase extraction followed by liquid chromatography/electrospray ion trap multiple-stage mass spectrometry

Matrix solid-phase dispersion (MSPD) is a new sample pretreatment for solid samples. This technique greatly simplifies sample pretreatment but, nonetheless, the extracts often still require an extra cleanup step that is both laborious and time-consuming. The potential of combining MSPD with molecularly imprinted solid-phase extraction (MISPE) was investigated in this study. Liver samples were ground in a mortar with C18 sorbent and the homogenized mixture packed into an SPE cartridge and placed on top of a MISPE cartridge. Subsequently, clenbuterol was eluted from the MSPD cartridge onto the MISPE cartridge using acetonitrile containing 1% acetic acid. The ability of the molecularly imprinted polymer to selectively adsorb analyte in acetonitrile was exploited for re-extracting clenbuterol directly from this acetonitrile extract via the double cartridge tandem system. The analyte was eluted from the MISPE cartridge using acidified methanol. A clear eluate was obtained, which was subsequently evaporated, redissolved, and analyzed by HPLC electrochemical detection (ECD) or ion trap mass spectrometry (LC/IT-MS). The MISPE cartridge used in this study was imprinted using bromoclenbuterol, a structural analogue of clenbuterol, as the template. These MISPE cartridges showed excellent stability. The complete extraction procedure was rapid, and recoveries exceeded 90% for the target analyte. The method detection limit for the LC/IT-MS procedure was < 0.1 microg/kg. This method, therefore, satisfies the stringent requirements of European Union regulation EEC 2377/90.     

Hybrid field-assisted solid-liquid-solid dispersive extraction for the determination of organochlorine pesticides in tobacco with gas chromatography

A novel one-step sample preparation technique termed hybrid field-assisted solid-liquid-solid dispersive extraction (HF-SLSDE) was developed in this study. A simple glass system equipped with a condenser was designed as an extraction vessel. The HF-SLSDE technique was a three-phase dispersive extraction approach. Target analytes were extracted from the sample into the extraction solvent enhanced by the hybrid field. Meanwhile, the interfering components were adsorbed by dispersing sorbent. No cleanup step preceded chromatographic analysis. The efficiency of the HF-SLSDE approach was demonstrated in the determination of organochlorine pesticide (OCP) residues in tobacco with a gas chromatography-electron capture detector (GC-ECD). Various operation conditions were studied systematically. Low detection limits (0.3-1.6 μg/kg) and low quantification limits (1.0-4.5 μg/kg) were achieved under the optimized conditions. The recoveries of OCPs ranged from 70.2% to 118.2%, with relative standard deviations of <9.6%, except for the lowest fortification level. Because of the effect of the hybrid field, HF-SLSDE showed significant predominance compared with other extraction techniques. The dispersing sorbent with good cleanup ability used in this study was also found to be a microwave absorption medium, which could heat the nonpolar extraction solvent under microwave irradiation. Different microstructures of tobacco samples before and after extractions demonstrated the mechanism of HF-SLSDE was based on an explosion at the cell level. According to the results, HF-SLSDE was proved to be a simple and effective sample preparation method for the analysis of pesticide residues in solid samples and could potentially be extended to other nonpolar target analytes in a complex matrix.     

固相萃取-双柱气相色谱法测定水中多种有机磷农药残留

针对单一气相色谱柱定性分析易出现假阳性误判的情况,采用固相萃取-气相色谱双柱技术测定环境水体中多种有机磷农药的残留量。水样中的有机磷农药通过HLB固相萃取小柱富集,经洗脱浓缩后,用DB-35MS和HP-5毛细管气相色谱柱、火焰光度检测器测定。方法的平均加标回收率为86.1%～118%,相对标准偏差为3.2%～6.8%,最低检出限为20～40ng/L,可满足环境水体中痕量有机磷农药残留的分析需要。     

基于GC-MS法测定纸质包装中4种二苯甲酮类物质

目的 利用气相色谱-质谱联用(GC-MS)法进行纸质包装中4种二苯甲酮类物质的测定.方法 优化超声提取纸质包装材料中二苯甲酮类光引发剂的方法,提取液使用GC-MS进行分析,采用全扫描和离子扫描方式确认每个物质的定性和定量离子.验证该方法的检出限、定量限、线性范围、相对标准偏差和回收率后用于实际样品的分析.结果 得到优化后的超声提取条件,乙腈作为提取溶剂,超声提取2次,每次提取时间为20 min.4种二苯甲酮类物质的检出限为0.01～0.05 mg/L,定量限为0.02～0.10 mg/L,标准添加实验的结果显示,相对标准偏差为2.0％～2.6％,回收率为98％～105％.结论 该方法检出限和定量限均较低,精密度和准确度较高,适合于实际纸质包装样品中4种二苯甲酮类物质的分析.     

Analysis of nicotine and its oxidation products in nicotine chewing gum by a molecularly imprinted solid-phase extraction

Chromatographic stationary phases showing exceptional selectivity for nicotine can be prepared by the technique of molecular imprinting. Such phases were used in the search for a rapid cleanup step for nicotine and some of its oxidation products in chewing gum formulations. Thus, using an organic mobile phase, the nicotine analytes from chewing gums dissolved in nonpolar solvent were retained, whereas the nonpolar matrix eluted close to the void peak. A subsequent switch to an acidic mobile phase resulted in elution of the analytes as one sharp peak. Due to weak binding of the less basic oxidation products, other imprinted polymers were tested, and the solid-phase extraction procedure was optimized. Polymers were prepared using various functional and cross-linking monomers, templates, porogens and thermal treatments. This resulted in phases that, when compared with a nonimprinted or a C18 reversed-phase column, showed significantly higher recoveries of the analytes. Furthermore, no bleeding of template from the phases could be detected. The cleanup step was coupled off-line to reversed-phase HPLC, and the efficiency of the analysis was compared with and without the cleanup step. Three out of four analytes were quantitatively recovered using the imprinted phase, whereas, using the nonimprinted phase, only nicotine was recovered. Without the cleanup step, none of the analytes could be determined using the reversed-phase HPLC method.     

Evaluation of a multidimensional solid-phase extraction platform for highly selective on-line cleanup and high-throughput LC-MS analysis of triazines in river water samples using molecularly imprinted polymers

A novel highly selective sample cleanup procedure based on the use of molecularly imprinted polymers (MIPs) as solid-phase extraction materials has been evaluated with respect to its applicability and routine use in environmental analysis. The method comprises the combination of a restricted access material (RAM) and a MIP allowing a selective sample preparation to be achieved in the online mode. This combination is called the size-selective sample separation and solvent switch (six-SPE). The RAM column combines size exclusion and adsorption chromatography, reducing the concentration of matrix molecules by a cutoff of 15 kDa. The MIP column selectively retains the triazine analytes whereas the residual matrix is not retained and separated completely. Thus, the automated RAM-MIP is capable of excluding all matrix and nontarget compounds. The cleaned and enriched extract is subsequently eluted to an HPLC column and analyzed by LC-MS. A complete on-line analysis cycle including multidimensional solid-phase extraction, separation, and detection takes less than 15 min. Terbuthylazine, atrazine, propazine, simazine, ametryn, prometryn, irgarol, and also the metabolites deethylatrazine and deisopropylatrazine can be determined without any matrix interferences, e.g., by humic acids. The whole setup is fully automated and may be continuously operated. Nonspecific interactions with the polymer are below 1% in all cases. The accuracy of the LC-MIP-LC-MS system was controlled using a certified reference material (Aquacheck). The applicability of the method to the cleanup of real samples was demonstrated by injection of contaminated river water samples. The stability of different polymers was tested by consecutive injections, and it was shown that the performance of the materials did not vary even after more than 300 enrichment and desorption cycles.     

Reducing time and increasing sensitivity in sample preparation for adherent mammalian cell metabolomics

A simple, fast, and reproducible sample preparation procedure was developed for relative quantification of metabolites in adherent mammalian cells using the clonal β-cell line INS-1 as a model sample. The method was developed by evaluating the effect of different sample preparation procedures on high performance liquid chromatography- mass spectrometry quantification of 27 metabolites involved in glycolysis and the tricarboxylic acid cycle on a directed basis as well as for all detectable chromatographic features on an undirected basis. We demonstrate that a rapid water rinse step prior to quenching of metabolism reduces components that suppress electrospray ionization thereby increasing signal for 26 of 27 targeted metabolites and increasing total number of detected features from 237 to 452 with no detectable change of metabolite content. A novel quenching technique is employed which involves addition of liquid nitrogen directly to the culture dish and allows for samples to be stored at -80 °C for at least 7 d before extraction. Separation of quenching and extraction steps provides the benefit of increased experimental convenience and sample stability while maintaining metabolite content similar to techniques that employ simultaneous quenching and extraction with cold organic solvent. The extraction solvent 9:1 methanol: chloroform was found to provide superior performance over acetonitrile, ethanol, and methanol with respect to metabolite recovery and extract stability. Maximal recovery was achieved using a single rapid (～1 min) extraction step. The utility of this rapid preparation method (～5 min) was demonstrated through precise metabolite measurements (11% average relative standard deviation without internal standards) associated with step changes in glucose concentration that evoke insulin secretion in the clonal β-cell line INS-1.     

Kinetic calibration for automated headspace liquid-phase microextraction

The kinetics of the absorption and desorption of analytes for headspace liquid-phase microextraction (HS-LPME) were studied. It was found that the desorption of analytes from the extraction phase into the sample matrix is isotropic to the absorption of the analytes from the sample matrix into the extraction phase under the same conditions. This therefore allows for the calibration of absorption using desorption. Calibration was accomplished by exposing the extraction phase, which contained a standard, to the sample matrix. The information from the desorption of the standard, such as time constant a, could be directly used to estimate the concentration of the target analyte in the sample matrix. This new kinetic calibration method for headspace LPME was successfully used to correct the matrix effects in the BTEX analysis of an orange juice sample. In this study, the headspace LPME techniques were successfully fully automated, for both static and dynamic methods, with the CTC CombiPal autosampler. All operations of headspace LPME, including sample transfer and agitation, filling of extraction solvent, exposing the solvent in the headspace, withdrawing the solvent to syringe and introducing the extraction phase into injector, were autoperformed by the CTC autosampler. The fully automated headspace LPME technique is more convenient and improved the precision and sensitivity of the method. This automated dynamic headspace LPME technique can be also used to obtain the distribution coefficient between the sample matrix (aqueous or another solution) and the extraction phase (1-octanol or another solvent). The distribution coefficient between 1-octanol and orange juice, at 25 degrees C, was obtained with this technique.     

Supercritical fluid extraction of natural antioxidants from rosemary: comparison with liquid solvent sonication

Supercritical fluid extraction (SFE) and liquid solvent sonication, in combination with two different sample treatments, were compared for the extraction of natural antioxidants from rosemary leaves. Dried, ground, and sieved rosemary leaves (20 mg) were subjected to SFE with CO(2) at 355 bar at 100 °C (CO(2) density 0.72 g/mL) for 20 min at a liquid flow rate of 4 mL/min. The analytes were concentrated on an ODS trap and subsequently eluted with acetone. Antioxidants in the SF and liquid solvent extract were analyzed by HPLC. Compounds of known antioxidant activity such as carnosol, carnosic acid, and methyl carnosate were identified by mass spectrometry of the HPLC fractions collected. Freezing and grinding the samples in liquid nitrogen resulted in decreased carnosic acid recoveries. Supercritical CO(2) extraction provided the highest recovery of carnosic acid from rosemary leaves (35.7 mg/g), the lowest relative standard deviation (4.4%), and the cleanest extract [Formula: see text] no cleanup prior to HPLC was required. Among the liquid solvents studies, only acetone provided comparable results (73% recovery relative to SC-CO(2) extraction); however, it required decoloration with active carbon prior to HPLC analysis.     

Optimization of the coating procedure for a high-throughput 96-blade solid phase microextraction system coupled with LC-MS/MS for analysis of complex samples

Biocompatible C18-polyacrylonitrile (PAN) coating was used as the extraction phase for an automated 96-blade solid phase microextraction (SPME) system with thin-film geometry. Three different methods of coating preparation (dipping, brush painting, and spraying) were evaluated; the spraying method was optimum in terms of its stability and reusability. The high-throughput sample preparation was achieved by using a robotic autosampler that enabled simultaneous preparation of 96 samples in 96-well-plate format. The increased volume of the extraction phase of the C18-PAN thin film coating resulted in significant enhancement in the extraction recovery when compared with that of the C18-PAN rod fibers. Various factors, such as reusability, reproducibility, pH stability, and reliability of the coating were evaluated. The results showed that the C18-PAN 96-blade SPME coating presented good extraction recovery, long-term reusability, good reproducibility, and biocompatibility. The limits of detection and quantitation were in the ranges of 0.1-0.3 and 0.5-1 ng/mL for all four analytes.