UPLC指纹图谱在烟用香精质量控制中的应用研究

为快速有效地控制不同批次烟用香精的质量,采用超高效液相色谱法(UPLC)法对同种香精9个不同批次样品的成分进行分析,通过计算色谱峰的相对保留值(a)和相对峰面积(Sr)建立香精样品的指纹图谱,并通过指纹图谱的聚类分析和主成分分析对样品进行模式识别.结果表明:聚类分析和主成分分析能够区分稀释及掺兑的香精样品,验证该方法的准确、可行性,可以作为香精质量稳定性控制的一种有效手段.     

色谱指纹图谱分析在香精香料质量控制中的应用

针对复杂的烟草香精香料化学成分,首先采用了3种不同的提取技术:同时蒸馏萃取(SDE),液液萃取(LLE)和固相微萃取(SPME)进行提取,在比较了它们的效果之后,采用了SDE和GC-MS相结合的方法建立了一种新的色谱指纹图谱方法。通过12个来自不同批次的烟草香精样品建立的指纹图谱分析,结果显示有39种挥发性成分(占总量的86.54%)能够被识别,其中有28个共有峰,基于共有峰的相对保留时间和相对峰面积进行的相似性分析表明:12个烟草香精样品的相似度均大于0.8,这说明不同批次的样品品质在一定程度上是稳定的。通过相似度比较和主成分分析,这种色谱指纹图谱能够轻松区别烟草香精和烟叶提取物,完全能够用于烟草香精的质量控制。     

HS-IMR-MS法在香精香料质量控制中的应用

为快速有效地评价不同厂家同种香精香料的质量,采用顶空-离子分子反应质谱(HS-IMR-MS)对同种香精8个不同批次的挥发性成分进行分析,研究不同电离源、顶空平衡温度及平衡时间对分析结果的影响,通过计算离子峰的相对强度,建立该香精的数字化质谱指纹图谱,并以数字化质谱指纹图谱为参照,利用主成分分析进行模式识别,对8个不同厂家提供的该种香精和3个掺杂样品的质量进行评价。结果表明:此法能快速对香精香料质量一致性进行评价,为香精香料质量控制提供一种新方法。     

烟用香精香料的高效液相色谱-蒸发光散射法质量控制研究

为了监控烟用香精香料的质量,应用高效液相色谱-蒸发光散射仪,Nova-Pak C18柱(4μm,150mm×3.9mm),以烟酸甲酯为内标,乙醇-水(71:29)为流动相,等度洗脱,流速1.0mL/min,对烟用香精香料进行HPLC分析,通过对待测样品与标准样品的指纹图谱谱峰匹配,计算指纹图谱间的相似度考察烟用香精香料质量稳定性。     

超声波萃取-气相色谱-质谱法同时测定土壤中16种多环芳烃和18种多氯联苯

建立超声波萃取结合气相色谱-质谱法(GC-MS)同时分析土壤中16种多环芳烃(PAHs)和18种多氯联苯(PCBs)的方法,并比较不同萃取方式、超声萃取时间和萃取次数等对加标回收率的影响.得到最佳检测方法为10.0 g样品用20 mL的正己烷和丙酮混合液(体积比1:1)超声波萃取15 min,萃取4次,萃取液经过浓缩、...     

RP-HPLC在烟用香精香料绿原酸、异构体测定中的应用

文章通过建立RP-HPLC反相高效液相色谱法,对烟用香精香料中的绿原酸及其异构体的分析测定原理过程进行分析,并结合该方法进行烟用香精香料绿原酸及其异构体测定中的应用情况,对于RP-HPLC在烟用香精香料绿原酸及其异构体测定中的应用进行分析论述。     

烟用香精香料分析测试

烟用香精香料化学成分复杂,对其化学成分分析具有一定的难度,首先要对香精香料进行适当的前处理,再选择适当的仪器进行分析测试,依据不同的分析方法和香精香料的性质而选择不同的前处理方法。     

固相微萃取—气相色谱—质谱法在烟草香味成分分析中的应用

采用固相微萃取-气相色谱-质谱(SPME-GC-MS)法定性分析烟叶和成品烟的挥发性香味成分,共鉴定了烟叶中的29种挥发性成分和成品烟中的20种挥发性成分。该方法简单、快速,适用于烟草样品的定性分析检测。     

加强烟用香精香料质量控制的探讨

该文对烟用香精香料这一特殊产品进行介绍,就烟用香精香料在烟草行业中的质量控制以具体的检测实验进行对比,通过常规物理实验和气相色谱-质谱分析方法的比较,说明各方法在香精香料质量控制中优劣,并就烟用香精香料检测室在实验室管理和统计技术等方面的提高提出建议。     

顶空固相微萃取气质联用法分析包装印刷品关键气味成分

目的 采用顶空固相微萃取技术（HS-SPME）结合气质联用（GC-MS）技术分析5款包装印刷品中对气味贡献较大的成分。方法 通过考察不同类型的萃取头、平衡时间、萃取时间和萃取温度对挥发性/半挥发性成分的数量及含量的影响,建立一种包装印刷品气味成分检测方法。结合解卷积+匹配度法+保留指数法对检测出的化合物进行定性识别,通过归一化法和内标法对气味成分的含量进行分析,并结合化合物的气味阈值,筛选关键气味成分。结果 得到了最佳的分析条件,采用50/30μm聚二乙烯苯/碳分子筛/聚二甲基硅氧烷固相微萃取头,平衡时间为30 min,萃取时间为30 min,萃取温度为80°C,解吸时间为10min。在上述最优条件下,5款包装印刷品被鉴别出43种关键性气味成分,包括醛类、酮类、醇类、芳香烃类、杂环类、酯类、醚类、胺类等八大类。结论 该方法可为后续包装印刷品气味分析、异味预警、新产品开发、工艺技术改进等提供技术支撑。     

不同部位烤烟中香味成分的分析研究

采用同时蒸馏—萃取的前处理方法,对不同部位烤烟中的香味成份进行了气相色谱—质谱(GC/MS)法定性定量分析。以内标法测定了不同部位烟叶中的吡嗪、噻唑、吡咯等16种碱性香味成分;糠醛、芳樟醇、β-紫罗兰酮等17种中性香味成分;丙酸、2-甲基戊酸、苯甲酸和月桂酸等15种酸性成分。     

Application of microwave-assisted extraction to the analysis of PCBs and CBzs in fly ash from municipal solid waste incinerators

Polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs) are two classes of dioxin precursors formed in municipal solid waste incinerators (MSWIs) producing negative health effects similar to those of dioxins. Reducing the analytical time required for determining the concentrations of these compounds in MSWIs is important for quickly evaluating their importance and associated health risks. In the present study, microwave-assisted extraction (MAE) is compared with traditional Soxhlet extraction (SE) to determine the extraction efficiencies attained for PCB and CBz analysis. The efficiencies of MAE are compared with those of SE under various experimental conditions, using fly ash spiked with standards. Water is used as a safe and environmentally friendly solvent in MAE for PCB and CBz analyses and MAE has high extraction efficiency for spiked fly ash compared with that of SE. Furthermore, the extraction time and organic solvent consumption are reduced with MAE compared with SE. The optimum conditions for MAE established in this study are using a 30-ml volume of toluene/acetone (1/1) or a 15-ml volume of toluene, samples with less than 60% water content (WC), and an irradiation time of 15 min.     

提升KPCA方法特征抽取效率的算法设计

在PCA基础上发展出的KPCA方法能抽取样本的非线性特征分量。然而, 基于KPCA的特征抽取需计算所有训练样本与待抽取特征的样本间的核函数, 因此, 训练集的大小制约着特征抽取的效率。为了提高效率，假设特征空间中变换轴可由一部分训练样本(节点)线性表出，并设计了改进的KPCA算法(IKPCA)。该算法抽取某样本特征时，只需计算该样本与节点间的核函数即可。实验结果显示，IKPCA在对应较好性能的同时，具有明显的效率上的优势。     

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.     

Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its diphenylcarbazide complex on an Amberlite XAD-4 resin column

A method has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its diphenylcarbazide complex on an Amberlite XAD-4 resin column. The influence of acidity, stability of the column, sample volume, flow rate and interfering ions were studied in detail. The adsorbed complex could be eluted using acetone–sulfuric acid mixture and the concentration of chromium was determined using visible spectrophotometry. A detection limit of 6 μg L⁻¹ could be achieved. A preconcentration factor of 27 could be obtained for 400 mL sample volume. The validity of the method was checked in spiked water samples and electroplating wastewater.     

Sample preparation using a miniaturized supported liquid membrane device connected on-line to packed capillary liquid chromatography

A miniaturized supported liquid membrane device has been developed for sample preparation and connected on-line to a packed capillary liquid chromatograph. The device consists of hydrophobic polypropylene hollow fiber, inserted and fastened in a cylindrical channel in a Kel-F piece. The pores of the fiber are filled with an organic solvent, in this study 6-undecanone, thus forming a liquid membrane. The sample is pumped on the outside of the hollow fiber (donor), and the analytes are selectively enriched and trapped in the fiber lumen (acceptor). With this approach, the volume of the acceptor solution can be kept as low as 1-2 μL. This stagnant acceptor solution is then transferred through capillaries attached to the fiber ends to the LC system. The system was tested with a secondary amine (bambuterol), as a model substance in aqueous standard solutions as well as in plasma. The best extraction efficiency in aqueous solution, with an acceptor volume of 1.9 μL, was 32.5% at a donor flow rate of 2.5 μL/min. At flow rates above 20 μL/min, the concentration enrichment per time unit was approximately constant, at 0.9 times/min, i.e., 9 times enrichment in about 10 min. The overall repeatability (RSD) for spiked plasma samples was ～4% (n = 12). Linear calibration curves of peak area versus bambuterol concentration were obtained for both aqueous standard solutions and spiked plasma samples. The detection limit for bambuterol in plasma, after 10 min of extraction at a flow rate of 24 μL/min, was 80 nM.     

Automated in-tube solid-phase microextraction coupled with HPLC for the determination of N-nitrosamines in cell cultures

An automated in-tube solid-phase microextraction (SPME) HPLC analysis method for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and several metabolites has been developed. NNK is one of the tobacco-specific N-nitrosamines (TSNA), which has been linked to cancers associated with the use of or exposure to tobacco products. In-tube SPME is an on-line extraction technique in which analytes are extracted and concentrated from the sample directly into a coated capillary by repeated draw/eject steps. In this study, a tailor-made polypyrrole (PPY)-coated capillary and several commercially available capillaries (capillary GC columns) were used to evaluate their extraction efficiencies for NNK and several metabolites in cell cultures. Compared with commercial capillaries that were currently used for in-tube SPME, the PPY-coated capillary showed better extraction efficiency for all of the compounds studied. After optimization of the extraction conditions, NNK and five metabolite compounds were analyzed in spiked cell cultures, confirming the applicability of the developed method. Excellent linearity was observed for all compounds (av R2 = 0.9942) and detection limits that ranged from 20 to 250 ng/mL. The average within-day and between day variations (% RSD) were 2.9 and 3.6%, respectively. This automated extraction and analysis method simplified the determination of the TSNA, requiring a total sample analysis time of only approximately 30 min.     

Determination of 16 phthalate metabolites in urine using automated sample preparation and on-line preconcentration/high-performance liquid chromatography/tandem mass spectrometry

We developed an on-line solid-phase extraction (SPE) method, coupled with isotope dilution high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) and with automated sample preparation, to simultaneously quantify 16 phthalate metabolites in human urine. The method requires a silica-based monolithic column for the initial preconcentration of the phthalate metabolites from the urine and a silica-based conventional analytical column for the chromatographic separation of the analytes of interest. It uses small amounts of urine (100 microL), is sensitive (limits of detection range from 0.11 to 0.90 ng/mL), accurate (spiked recoveries are approximately 100%), and precise (the inter- and intraday coefficients of variation are <10%). The method is not labor intensive, and, because pretreatment of the urine samples was performed automatically using an HPLC autosampler, involves minimal sample handling, thus minimizing exposure to hazardous chemicals. The method was validated on spiked, pooled urine samples and on urine samples from 43 adults with no known exposure to phthalates. The high sensitivity and high throughput (HPLC run time, including the preconcentration step, is 27 min) of this analytical method combined with the ease of use and effective automated sample preparation procedure make it suitable for large epidemiological studies to evaluate the prevalence of human exposure to phthalates.     

An analytical method for trifluoroacetic Acid in water and air samples using headspace gas chromatographic determination of the methyl ester

An analytical method has been developed for the determination of trace levels of trifluoroacetic acid (TFA), an atmospheric breakdown product of several of the hydrofluorocarbon (HFC) and hydrochlorofluorocarbon (HCFC) replacements for the chlorofluorocarbon (CFC) refrigerants, in water and air. TFA is derivatized to the volatile methyl trifluoroacetate (MTFA) and determined by automated headspace gas chromatography (HSGC) with electron-capture detection or manual HSGC using GC/MS in the selected ion monitoring (SIM) mode. The method is based on the reaction of an aqueous sample containing TFA with dimethyl sulfate (DMS) in concentrated sulfuric acid in a sealed headspace vial under conditions favoring distribution of MTFA to the vapor phase. Water samples are prepared by evaporative concentration, during which TFA is retained as the anion, followed by extraction with diethyl ether of the acidified sample and then back-extraction of TFA (as the anion) in aqueous bicarbonate solution. The extraction step is required for samples with a relatively high background of other salts and organic materials. Air samples are collected in sodium bicarbonate-glycerin-coated glass denuder tubes and prepared by rinsing the denuder contents with water to form an aqueous sample for derivatization and analysis. Recoveries of TFA from spiked water, with and without evaporative concentration, and from spiked air were quantitative, with estimated detection limits of 10 ng/mL (unconcentrated) and 25 pg/mL (concentrated 250 mL:1 mL) for water and 1 ng/m(3) (72 h at 5 L/min) for air. Several environmental air, fogwater, rainwater, and surface water samples were successfully analyzed; many showed the presence of TFA.