固相萃取-GC-MS法测定水中四氯联苯

建立全自动固相萃取-气相色谱-质谱法检测水中微量四氯联苯的方法。采用全自动固相萃取装置配有C_(18)固相萃取盘富集浓缩水中四氯联苯后,用乙酸乙酯和二氯甲烷洗脱,以CD-5MS毛细管色谱柱分离,气相色谱质谱法测定水中四氯联苯的含量。对水样的洗脱剂、萃取流速、pH值、甲醇加入量等进行了优化试验,四氯联苯PCB52,PCB77,PCB81的质量浓度在5.00~50.0μg/L范围内与色谱峰面积呈良好的线性,检出限分别为0.002,0.003,0.002μg/L;加标回收率分别为90.9%,92.7%,95.4%;测定结果的相对标准偏差均小于3%(n=7)。该方法灵敏度高,适用于水样中痕量四氯联苯的监测。     

固相萃取–气相色谱–质谱法测定地表水中的三氯苯

建立固相萃取–气相色谱–质谱联用法测定地表水中三氯苯的方法,对固相萃取柱、洗脱剂、甲醇用量进行优化试验。在200 m L水样中加入20 m L甲醇,采用C18固相萃取柱,以正己烷为洗脱溶剂萃取水中的三氯苯,用气相色谱–质谱法测定。结果表明,三氯苯的三种同分异构体分离良好,1,2,3-三氯苯、1,2,4-三氯苯、1,3,5-三氯苯的质量浓度在2.0~100μg/L范围内与其色谱峰面积均呈良好的线性,线性相关系数分别为0.999 1,0.999 4,0.999 2,检出限分别为0.004,0.005,0.005μg/L,加标回收率为90.3%~96.5%,测定结果的相对标准偏差均小于2%(n=7)。该方法操作简便、快速,定性定量准确,有机试剂用量少,适用于地表水中三氯苯的检测。     

银离子固相萃取-气相色谱法检测乳脂肪中的反式脂肪酸

建立了分离反式油酸(C18:1)、亚油酸(C18:2)、亚麻酸(C18:3)的银离子固相萃取-气相色谱(Ag+-SPE/GC)方法,并应用于乳脂肪中反式脂肪酸的检测。采用自制的银离子固相萃取柱对样品进行预分离,总脂肪酸甲酯化后上样,依次经9 mL甲苯-正己烷(体积比5:95)、8 mL甲苯-正己烷(体积比17:83)、6 mL甲苯-乙酸乙酯(体积比17:83)、10 mL甲苯-乙酸乙酯(体积比30:70)洗脱并分别收集洗脱液,采用气相色谱分别进行检测。结果显示,除了反式亚麻酸的回收率为69.9%～101.0%、相对标准偏差(RSD)为11.0%～18.1%外,其余的反式脂肪酸的回收率均为88.4%～107.2%、RSD为1.2%～11.9%。该方法通过特异性固相萃取的方法对样品进行前处理,较好地避免了样品中顺式及饱和脂肪酸对反式脂肪酸检测的干扰。     

固相萃取-离子色谱法测定甘蔗糖蜜及糖蜜酒精废液中的非氮有机酸和无机阴离子

建立了固相萃取-离子色谱测定甘蔗糖蜜及糖蜜酒精废液中乙酸、乳酸、琥珀酸、苹果酸、酒石酸、草酸、富马酸、柠檬酸、乌头酸等非氮有机酸和盐酸根、硫酸根、磷酸根等3种无机阴离子的方法。样品稀释液经强阴离子(SAX)固相萃取小柱净化除去糖类和色素等干扰基质,再用稀KOH溶液洗脱,经0.45 μm水膜过滤后,用IonPac AS15阴离子分离柱、KOH溶液梯度淋洗-抑制电导检测分离分析。考察了固相萃取小柱对待测离子的保留和洗脱条件。实验结果表明,除乙酸和乳酸的分离不完全、苹果酸与琥珀酸的组分重叠外,其余组分可达到完全分离,被测组分的浓度与其峰高在一定的范围呈良好的线性关系,检出限均低于0.20 mg/L,相对标准偏差(RSD)小于6.7%。测定了2种甘蔗糖蜜和1种糖蜜酒精废液中有机酸及无机阴离子,结果满足检测的要求,样品中各组分的加标回收率为94%～109%。     

固相萃取-气相色谱-质谱法分析电子烟烟液中的香味成分

为了检测电子烟烟液中的香味成分,建立了固相萃取-气相色谱质谱检测方法。利用Li Chrolut EN固相萃取柱富集香味成分,以二氯甲烷为洗脱剂,洗脱液用气相色谱串联质谱分析。方法能有效富集烟液中的香味物质,排除雾化剂(甘油、丙二醇)对香味成分的干扰;重复性较好,大部分化合物峰面积相对标准偏差小于10%。利用该方法分析了4种烟液样品,结果不同口味电子烟所含香味成分差别较大。     

固相萃取-毛细管气相色谱法测定生活饮用水中16种硝基苯类化合物

建立了生活饮用水中16种硝基苯类物质的固相萃取-毛细管气相色谱-电子捕获检测方法.实验优化了色谱柱、升温程序等色谱条件,并对影响固相萃取效果的主要因素(萃取小柱、洗脱剂和洗脱体积)进行了考察.水样中16种硝基苯类物质经Oasis HLB固相萃取柱吸附、正己烷-丙酮(3∶1,V/V)洗脱后,采用DB-1701毛细管气相色谱柱程序升温分离、ECD检测,在33 min内完成所有待测组分的测定.16种硝基苯类组分在各自的线性范围内相关系数r≥0.998,方法的检出限为0.01 ～0.77 μg/L(S/N=3),定量限为0.03 ～2.57 μg/L(S/N=10),日内精度和日间精度分别在1.0％ ～ 3.8％和2.3％～4.8％间,样品加标回收率为83.6％～ 111.8％,加标样品的RSD为1.2％ ～5.1％.应用本方法对50份水样进行了分析,结果表明,本方法准确、灵敏、快速,适用于水质的常规分析,可为水样中硝基苯类物质的污染评价提供技术支持.     

液液提取-固相萃取-气相色谱法测定牛肉中蝇毒磷残留量的研究

建立了液液提取-固相萃取-气相色谱火焰光度法(LLE-SPE-GC-FPD)测定牛肉中蝇毒磷的残留量.优化了气相色谱分离条件,研究了样品基质对蝇毒磷测定的影响,考察了Florisil固相萃取小柱和ODS固相萃取小柱的萃取效果,并选择乙酸乙酯为洗脱剂,考察了液-液提取和固相萃取的回收率.将该方法用于牛肉中蝇毒磷的测定,其检出限为0.02 μg/mL,回收率高于83%,相对标准偏差13.7%.使用气相色谱质谱仪(GC-MS)对样品中的蝇毒磷进行定性分析,其特征离子和相对丰度为362(100)、226(55)和210(40).     

固相萃取-气相色谱法测定鱼塘投毒案件水样中硫丹的含量

采用固相萃取-气相色谱法测定鱼塘投毒案件水样中硫丹的含量。取自鱼塘的水样调至pH 4,经CNWBOND LC-C18固相萃取柱分离,用三氯甲烷作为洗脱溶剂,所得提取液用CP-SIL8毛细管色谱柱分离,电子捕获检测器检测。α-硫丹和β-硫丹的峰面积与其质量浓度在0.05~5μg·L-1相同的范围内呈线性关系,方法的检出限(3S/N)均为0.01μg·L-1。加标回收率在91.1%~95.8%之间,测定值的相对标准偏差(n=6)小于1%。     

固相萃取–气相色谱法测定水中三卤甲烷

建立固相萃取–气相色谱法测定水中三卤甲烷的含量。考察了固相萃取柱、洗脱剂、氯化钠加入量和水样p H值对待测物萃取效果的影响。水样经C18固相萃取柱富集,乙酸乙酯和二氯甲烷洗脱,经气相色谱电子捕获检测器检测,三卤甲烷各组分分离良好。三卤甲烷的质量浓度在0.00~40.0μg/L范围内与对应的色谱峰面积均呈良好线性关系,线性相关系数大于0.999,三卤甲烷加标回收率为91.4%~104.0%,测定结果的相对标准偏差均小于1.5%(n=6)。该方法操作简便,准确度、精密度好,灵敏度高,检出限低,适用于水中三卤甲烷的测定。     

气相色谱法测定生活饮用水中2-氯苯酚和2-甲苯酚

采用固相萃取(SPE)小柱固相萃取,建立了生活饮用水中2-氯苯酚和2-甲苯酚的气相色谱检测方法。用盐酸调节水样至p H 5.0,用SPE小柱固相萃取后以乙酸乙酯洗脱,以CD-5色谱柱进行分离,氢火焰离子化检测器检测2-氯苯酚和2-甲苯酚的含量。2-氯苯酚和2-甲苯酚的质量浓度在2.00~40.0μg/L范围内与色谱峰面积线性关系良好,检出限分别为0.03,0.04μg/L;加标回收率分别为87.2%~93.9%,89.0%~94.8%;测定结果的相对标准偏差均小于2%(n=7)。该方法具有检出限低、操作简便等优点,适用于生活饮用水中2-氯苯酚和2-甲苯酚的监测分析。     

Simultaneous determination of amounts of major phospholipid classes and their fatty acid composition in erythrocyte membranes using high-performance liquid chromatography and gas chromatography.

A method for the simultaneous determination of amounts of major phospholipid classes and their fatty acid composition in erythrocyte membranes is described. The method consists in extraction of phospholipids from erythrocyte membranes, separation of phospholipid classes by high-performance liquid chromatography, methylation of phospholipids and determination of phospholipid-bound fatty acids by capillary gas chromatography. The amounts of phospholipid classes are calculated from the total weight of phospholipid-bound fatty acids and their average molecular weights. The method was applied to erythrocytes from rats. The results show that the method is reproducible and is useful for the determination of amounts of phospholipid classes and their fatty acid composition in small blood samples.     

Simultaneous determination of short‐chain fatty acids in human feces by HPLC with ultraviolet detection following chemical derivatization and solid‐phase extraction segmental elution

Short‐chain fatty acids are currently the most studied metabolites of gut microbiota, but the analysis of them, simultaneously, is still challenging due to their unique property and wide concentration range. Here, we developed a sensitive and versatile high‐performance liquid chromatography with ultraviolet detection method, using pre‐column derivatization and solid‐phase extraction segmental elution, for the quantification of both major and trace amounts of short‐chain fatty acids in human feces. Short‐chain fatty acids were converted to 3‐nitrophenylhydrazine‐derived analytes, and then solid‐phase extraction segmental elution was used for extraction of major analytes and enrichment of trace analytes. The method validation showed limits of quantitation ?0.04 mM, and coefficient of determination > 0.998 at a wide range of 0.04–8.0 mM. The intra‐ and interday precision of analytes were all within accepted criteria, and the recoveries were 96.12 to 100.75% for targeted analytes in fecal samples. This method was successfully applied in quantification of eight analytes in human feces, which therefore could provide a sensitive and versatile high‐performance liquid chromatography with ultraviolet detection method for precise and accurate quantitation of short‐chain fatty acids in human feces.     

Quantification of fatty acids as methyl esters and phospholipids in cheese samples after separation of triacylglycerides and phospholipids

Determination of the individual fatty acid composition of neutral- and phospholipids as well as the phospholipid content of dairy food and other foodstuffs are important tasks in life sciences. For these purposes, a method was developed for the separation of lipids (standards of triolein and diacylphosphatidylcholines as well as three cheese samples) by solid-phase extraction using a self-packed column filled with partly deactivated silica. Non-halogenated solvents were used for the elution of the lipid classes. Cyclohexane/ethyl acetate (1:1, v/v) served for the elution of neutral lipids, while polar lipids were eluted with three solvents (ethyl acetate/methanol, methanol, and methanol/water) into one fraction. The separated lipid fractions were transesterified and the individual fatty acids were quantified by using gas chromatography coupled to electron ionization mass spectrometry (GC/EI-MS) in the selected ion monitoring (SIM) mode. The recovery rate for standard phosphatidylcholines was ∼90% and cross-contamination from neutral lipids was negligible. The method was applied to cheese samples. Quantitative amounts of individual fatty acids in the phospholipid fraction were <0.002-0.29% of total lipids from camembert, <0.002-0.12% of total lipids from mozzarella, and <0.002-0.18% of total lipids in a goat cream cheese. Differences in the fatty acid pattern of neutral and polar lipids were detected. The quantity of the fatty acids determined in the phospholipid fraction was divided by the factor 0.7 in order to convert the fatty acid content into the phospholipid content of the cheese samples. This factor is based on the contribution of 16:0 to dipalmitoylphosphatidylcholine (DPPC). The resulting DPPC equivalents (DPPC_eq) were found to be representative for the average contribution of fatty acids to all classes of phospholipids in dairy products. Using this approach, the phospholipid content of lipids from mozzarella, camembert, and goat cream cheese was 0.60%, 1.42% and 0.79%, respectively.     

Analysis of fatty acids in mouse cells using reversed-phase high-performance liquid chromatography

Summary A reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed to analyze various fatty acids in recombinant mouse L cells. These fatty acids were the metabolites of oleic acid. A process was developed to extract fatty acids from the cell samples before RP-HPLC analysis. The samples were first saponified with 0.5 M NaOH in 96% ethanol then extracted with acidified ethyl acetate. After extraction, the sample was dried and dissolved in HPLC-grade methanol. After centrifugation to remove insoluble impurities, the sample was applied to a C₁₈RP-HPLC column using a gradient of acetonitrile (ACN)-H₂O. The eluted fatty acids were monitored by ultraviolet (UV) absorption at 195 nm and identified by retention time and adsorption spectrum comparison. This method successfully resolved various fatty acids and provided a tool for the elucidation of the fatty acid metabolic pathway in the cells.     

Determination of vitamin A in blood serum based on solid‐phase extraction using cetyltrimethyl ammonium bromide‐modified attapulgite

Cetyltrimethyl ammonium bromide‐modified attapulgite was prepared and utilized as a novel sorbent in a simple solid‐phase extraction method for the determination of vitamin A in blood serum. Several factors affecting extraction efficiency were systematically optimized, including the sampling solvent and its volume, as well as the elution solvent and its volume. Under the optimal solid‐phase extraction conditions, the adsorption capacity of vitamin A was as high as 28 mg/g according to the Langmuir isotherm model. Based on the developed solid‐phase extraction method, the level of vitamin A in 200 µL blood serum sample could be accurately determined by high‐performance liquid chromatography. The recoveries of vitamin A spiked in 10% v/v methanol aqueous solutions were in the range of 86.9–92.8%, with the relative standard deviations not more than 8.1%. The method was applied to the determination of vitamin A in serum samples from 20 pregnant women. Compared with the previously reported solid‐phase extraction methods for determination of vitamin A in serum, our developed cetyltrimethyl ammonium bromide‐modified attapulgite‐based solid‐phase extraction method used lower serum volume, omitted extra steps (i.e. evaporation and re‐dissolution), and eliminated internal standard. The results were promising for it to be used in routine monitoring during pregnancy.     

Improvement of a solid phase extraction method for analysis of lipid fractions in muscle foods

The most used method for muscle lipid fractionation into major lipid classes was modified for improving its separation efficiency. Extracted lipids from a masseter muscle of one Iberian pig were separated into neutral lipids (NL), free fatty acids (FFA) and polar lipids (PL) using aminopropyl minicolumns, following the extensively used method of Kaluzny et al. [1] (old method-OM-) and a method based on that, developed by Pinkart et al. [2] with some (modifications modified method–MM). Obtained lipid classes were further analysed by TLC and lipid fractions were identified. TLC evidenced the presence of a certain amount of PL in the NL fraction obtained with the OM. On the other hand, using the MM only an almost undetectable presence of PL was evidenced in the NL fraction. Fatty acid composition of NL, PL and FFA obtained with each method was studied by gas chromatography. Fatty acid profile of NL was strongly influenced by the separation method used. Thus, NL obtained using the OM showed higher amounts of saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) and lower of monounsaturated fatty acids (MUFA) than those obtained using the MM. Moreover, NL obtained using the OM showed the presence of fatty alcohols, constituents of phospholipids (PhL) absent or present only in trace amounts in acylglycerols. This profile reflects the coelution of PL in the NL fraction. Fatty acid profile of FFA and PL fractions was also influenced by the solid phase extraction (SPE) method used, but to a lesser extent.     

生物样品中短链脂肪酸的提取与测定

综述了生物样品(主要为粪便、尿液、血液和培养液)中短链脂肪酸的提取与测定方法,讨论了各种样品提取方法的优缺点,并比较了气相色谱、高效液相色谱和毛细管电泳分离检测的优点和局限性。引用文献63篇。     

Multiresidue determination of 114 multiclass pesticides in flue‐cured tobacco by solid‐phase extraction coupled with gas chromatography and tandem mass spectrometry

A sensitive and robust multiresidue method for the simultaneous analysis of 114 pesticides in tobacco was developed based on solid‐phase extraction coupled with gas chromatography and tandem mass spectrometry. In this strategy, tobacco samples were extracted with acetonitrile and cleaned up with a multilayer solid‐phase extraction cartridge Cleanert TPT using acetonitrile/toluene (3:1) as the elution solvent. Two internal standards of different polarity were used to meet simultaneous pesticides quantification demands in the tobacco matrix. Satisfactory linearity in the range of 10–500 ng/mL was obtained for all 114 pesticides with linear regression coefficients higher than 0.994. The limit of detection and limit of quantification values were 0.02–5.27 and 0.06–17.6 ng/g, respectively. For most of the pesticides, acceptable recoveries in the range of 70–120% and repeatabilities (relative standard deviation) of <11% were achieved at spiking levels of 20, 100, and 400 ng/g. Compared with the reported multiresidue analytical method, the proposed method provided a cleaner test solution with smaller amounts of pigments, fatty acids as well as other undesirable interferences. The development and validation of the high sensitivity, high selectivity, easy automation, and high‐throughput analytical method meant that it could be successfully used for the determination of pesticides in tobacco samples.     

Qualitative and quantitative determination of extractives in heartwood of Scots pine (Pinus sylvestris L.) by gas chromatography

A method for quantitative determination of extractives from heartwood of Scots pine (Pinus sylvestris L.) using gas chromatography (GC) with flame ionization detection (FID) was developed. The limit of detection (LOD) was 0.03 mg/g wood and the linear range (r = 0.9994) was up to 10 mg/g with accuracy within +/- 10% and precision of 18% relative standard deviation. The identification of the extractives was performed using gas chromatography combined with mass spectrometry (GC-MS). The yields of extraction by Soxhlet were tested for solid wood, small particles and fine powder. Small particles were chosen for further analysis. This treatment gave good yields of the most important extractives: pinosylvin, pinosylvin monomethyl ether, resin acids and free fatty acids. The method is used to demonstrate the variation of these extractives across stems and differences in north-south direction.     

Determination of free fatty acids in chocolate by liquid chromatography with tandem mass spectrometry

This paper describes a rapid extraction method, based on a matrix solid-phase dispersion technique using diatomaceous earth as solid support and 50:50 (v/v) chloroform/methanol as extracting solvent, that can determine 11 free fatty acids in chocolate. The extraction procedure is followed by reversed-phase liquid chromatography/tandem mass spectrometry (LC/MS/MS) using a normal-bore (4.6 mm i.d.) C-18 column and an electrospray interface operating in the negative ion mode. The tandem mass spectra of selected compounds show that charge-remote fragmentation (CRF) mechanisms are occurring; the intensities of the CRF reactions increase with the carbon number and degree of unsaturation of the fatty acids. Average recoveries, evaluated by the standard addition method, vary between 79-103%, and the estimated quantification limits are less than 153 ng/g. The proposed method has been used to analyse nine chocolate samples from various price ranges, bought from supermarkets.