在线液液液微萃取-电动流动分析系统测定水中挥发酚类化合物总量

采用在线液液液微萃取(LLLME)富集净化和电动流动分析(EFA)系统测定水中挥发酚类化合物折合苯酚总量.EFA系统由一台自制电渗泵和4个电磁切换阀组成,计算机控制泵运作和阀切换.结果表明:在聚丙烯中空纤维膜壁上涂十二醇液膜,管内充10 μL 0.25 mol/L NaOH反萃液,试样以2.0 mL/min流量流经萃取通道7.5次循环,1.0 mL样品体积的富集倍数为53,分析时间为 9 min,挥发酚类化合物折合浓度线性范围为9.4×10-3～5.7 mg/L苯酚,检出限为3 μg/L苯酚,远低于一和二级污水排放中挥发酚类化合物的最大允许量;6.0 mL样品体积的富集倍数为300,挥发酚类化合物折合浓度线性范围为1.7×10-3～1.0 mg/L苯酚,检出限为0.6 μg/L苯酚,低于Ⅰ和Ⅱ类地面水中挥发酚类化合物的最大允许量.     

毛细管电泳大体积进样在柱复合富集技术

提出场放大进样和酸堆积结合的大体积样品复合富集方法,实现了毛细管电泳对高盐样品中阳离 子的有效富集和分离。向样液中添加70%(V/V)乙腈,场放大进样600s后,电动注入强酸做酸堆积,预富集 样品带用毛细管区带电泳分离仍能获得满意的分离度。此法的富集倍数约为常规电动进样的800倍。普萘 洛尔和美托洛尔的检出限分别达到1×10-4mg/L和7×10-4mg/L     

大体积进样-浓缩柱在线富集-离子色谱法测定水中痕量及超痕量溴酸盐

建立了一种测定水中痕量及超痕量溴酸盐的在线富集大体积进样离子色谱法。采用实验室常备的柱容量较高的Dionex IonPac AG23保护柱作为浓缩柱,连接在定量环处富集溴酸盐。淋洗液自动发生装置在线生成高纯度氢氧化钾淋洗液进行梯度洗脱,抑制电导检测。实验结果表明:溴酸盐质量浓度范围在0.05~51.2 μg/L之间时线性关系良好,相关系数r≥0.9995,方法检出限为0.01 μg/L。与常规进样相比,进样量可高达5 mL,浓缩因子约为240倍。本方法成功应用于市售纯净水中溴酸盐的测定,2个加标水平的回收率在90%~100%之间,RSD(n=6)为2.1%~6.4%。该方法无需前处理,操作简单,准确度和精密度良好。通过大体积进样实现高倍富集,适用于痕量及超痕量溴酸盐的分析。     

胶束毛细管电泳在线扫集技术同时分离测定穿心莲内酯和脱水穿心莲内酯的研究

采用胶束毛细管电泳在线扫集技术分离测定了中药穿心莲中脱水穿心莲内酯和穿心莲内酯.电泳条件:以20 mmol/L H3BO310 mmol/L NaH2PO4-50mmol/L SDS(含体积分数20%甲醇,pH 2.4)为电泳运行缓冲溶液,未涂层石英毛细管(58 cm×50 μm i.d.,有效长度为41.2 cm)为分离通道,重力进样,进样高度为11 cm,-20 kV恒压,检测波长为246 nm.富集倍数可以达到200倍以上.在5.70～91.20 mg/L,和3.96～31.68 mg/L范围内呈良好的线性关系,对两种内酯分别进行了定量分析.加标平均回收率脱水穿心莲内酯为100.80%,穿心莲内酯为98.06%.     

阴离子选择性耗尽进样-胶束扫集毛细管电泳法对痕量醋酸氢化可的松的测定

联用阴离子选择性耗尽进样和胶束扫集两种在线富集技术,建立了胶束毛细管电泳方法测定化妆品中醋酸氢化可的松的方法。讨论了SDS浓度、样品基体、进样电压、进水时间和进样时间对富集和分离的影响。优化的实验条件:以120 mmol/L SDS-20 mmol/L NaH2PO4(pH2.2)-10%(体积分数)甲醇为缓冲体系,分离电压-20 kV,进样电压-20 kV,进样时间80 s,进水时间200 s,测量波长250 nm。在该实验条件下,醋酸氢化可的松的富集倍数比普通毛细管电泳法提高了约173倍。方法的线性范围为0.05~5.0 mg/L,检出限为12.6μg/L。该方法用于化妆品中醋酸氢化可的松含量的测定,回收率为98%~105%,相对标准偏差均小于4.0%(n=4)。     

大体积进样-非匀强电场扫集微乳毛细管电动色谱法测定化妆品中糖皮质激素

建立了一个简单有效的微乳毛细管电动色谱(MEEKC)在线富集-大体积进样(LVSI)与非匀强电场扫集(REFS)联用测定化妆品中4种糖皮质激素(泼尼松、氢化可的松、泼尼松龙和倍他米松)的方法。MEEKC的缓冲体系组成为:2.4%SDS,0.6%正辛烷,6.6%正丁醇,30 mmol/L硼酸盐缓冲液(pH 8.2),分离电压为9.6 kV,进样压力为12.3 kPa,进样时间为95 s,检测波长为230 nm。在最优实验条件下,4种糖皮质激素的富集倍数为853~933倍,在0.015~14 mg/L范围内呈线性关系,检出限(S/N=3)为4~8μg/L。应用此方法分析了化妆品样品,回收率为93.7%~103.8%,相对标准偏差(n=5)均不大于4.4%。     

壳聚糖在线微柱预富集火焰原子吸收光谱法测定矿石中的痕量金

报道了壳聚糖作在线微柱预富集填料,流动注射与火焰原子吸收光谱联用(FI-FAAS)测定痕量金的方法。将金与硫氰酸钾混合富集在壳聚糖上并以硫脲作洗脱剂。当采样体积10.3 mL时,采样频率36个样/h,富集倍数26倍。检出限(3σ,n=11)0.50μg.L-1,相对标准偏差1.4%(ρAu=0.10 mg/L)和2.4%(ρAu=0.01mg/L)。该方法用于矿石中金的测定,结果满意。并探讨了壳聚糖吸附金的机理。     

磁性纳米四氧化三铁选择性富集-电感耦合等离子体原子发射光谱测定砷

基于磁性纳米Fe3O4对砷的选择性富集作用,建立了电感耦合等离子体原子发射光谱(ICP-OES)测定水溶液中砷的方法.考察了溶液酸度、吸附时间、吸附剂用量、试液体积和共存离子等因素对不同形态砷分离富集效率的影响.结果表明,在pH 2～10范围内,选用6.0 mg纳米Fe3O4定量富集,振荡2 min后,三价砷、五价砷、一甲基砷以及二甲基砷等均可被磁性纳米Fe3O4定量富集.线性范围为0.063～20 mg/L; 检出限(3σ)为0.0189 mg/L; 对砷标准溶液测定的相对标准偏差为1.27%(n=6).用本方法对自来水中加入的砷标准溶液进行了测定,回收率为100.3%～104.8%.本方法简便快速,可用于复杂基体中低含量砷的富集分离和测定.     

酞酸酯的场增强样品进样-微乳液毛细管电动色谱分析

建立了场增强样品进样–微乳液毛细管电动色谱(microemulsion electrokinetic chromatography,MEEKC)分析6种酞酸酯的方法,对影响富集过程的因素进行了考察。最佳富集条件为:以压力进样先进一段水柱(5.52 kPa×500s),在富集电压为-15 kV下,样品以电动方式进样富集,样品基质为30mmol/L胆酸钠+30.0 mmol/L硼砂(pH 8.5)。与常规MEEKC方法相比,场增强样品进样在线富集技术使6种酞酸酯的检测灵敏度提高了1.6～1000倍,检测限(S/N=3)为1～500 ng/mL。所建立的方法用于食品塑料袋中酞酸酯的测定,加标回收率为92.5%～112.2%。     

反向微乳毛细管电泳法在线富集技术灵敏检测化妆品中的多环芳烃

要建立了反向微乳毛细管电泳(MEEKC)在线富集技术灵敏检测多环芳烃的方法。采用大体积进样-p H动态连接-扫集微乳毛细管电泳法(LVSS-Dyp H-MEEKC)对于常规条件下很难分离的6种强亲脂性的多环芳烃中性分子进行富集分离。结果表明,在反相电压下,当微乳液的组成为:2.4%(w/w)SDS、0.6%(w/w)正辛烷、6.6%(w/w)正丁醇、20 mmol/L Na H2PO4缓冲液(p H 2.2);进HCB时间为20 s(16 k Pa),进样时间为80 s(16 k Pa)时,富集效果良好,富集倍数在25~80倍之间,在27 min内实现了对多环芳烃化合物的灵敏检测。将本方法用于化妆品中多环芳烃的检测,回收率在90.6%~95.9%之间,相对标准偏差均小于5.1%(n=5)。     

Analysis of heavy organic pollutants of confined atmospheres

Summary An improved procedure for the determination of the less volatile air pollutants of recycled closed atmospheres by activated carbon-Soxhlet extraction is proposed. After total treatment of desorbate, PAH determination is then accomplished by RP-HPLC using both adsorptiometric and fluorimetric UV detection; phenolic compounds are determined by GC-MS.This technique is suitable for very low levels of PAH and phenolic compounds.     

Simultaneous extraction and analysis by high performance liquid chromatography coupled to diode array and mass spectrometric detectors of bixin and phenolic compounds from annatto seeds

This study was designed to identify and quantify the carotenoids and phenolic compounds from annatto seeds using high performance liquid chromatography coupled to diode array and mass spectrometer detectors (HPLC-DAD-MS/MS). Furthermore, using response surface methodology, an optimized procedure for simultaneous extraction of these compounds was established. In addition to bixin, known to be the main carotenoid in annatto seeds, hypolaetin and a caffeoyl acid derivative were identified as the main phenolic compounds. The optimized procedure involved 15 extractions using acetone:methanol:water (50:40:10, v/v/v) as solvent, a solid-liquid ratio of 1:9 (m/v) and an extraction time of 5 min. Validation data indicated that the HPLC method proposed provided good linearity, sensitivity, procedure accuracy, system precision and suggested its suitability for the simultaneous analysis of phenolic compounds and carotenoids in annatto seeds.     

Determination of antioxidant properties of 26 Chilean honeys and a mathematical association study with their volatile profile

Radical scavenging activity (RSA), antioxidant content (TEAC), total phenolic compounds content (TPCC) and volatile profile (VOCs) were measured in 26 honeys obtained from the Valparaiso Region (Chile). Persea americana honey was the most interesting sample according to these evaluated parameters. A Projection to Latent Structures (PLS) based algorithm was used to model the possible relationship between antioxidant activity, total phenolic compounds content and volatile profile. Concerning the volatile profile, only nine volatile compounds, of a total of fifty, showed dependence on antioxidant activity and total phenolic compounds content.     

固相萃取-气相色谱-串联质谱法检测水中18种酚类化合物

当前水中酚类化合物种类不清、危害不明，多种酚类化合物的同时检测方法不成熟，因此建立水中多种酚类化合物同时检测的方法具有重要现实意义。该研究建立了固相萃取结合气相色谱-串联质谱同时检测水中18种酚类化合物的分析方法。实验选择超纯水为空白样品，采用固相萃取技术富集、提取水中的酚类化合物，同时对水样初始pH值、洗脱液的种类、洗脱液的用量等条件进行优化，从而确定出最优的前处理方法，最后利用气相色谱-串联质谱法对不同种类的酚类化合物同时进行定量检测。实验结果表明，在初始水样pH值为3.0、不衍生等条件下，使用10 mL乙酸乙酯洗脱，控制洗脱速度为1 mL/min，经固相柱富集净化，氮吹浓缩后，用气相色谱-质谱仪（EI源）测定，选择离子模式监测，外标法定量。结果表明，以3倍信噪比结合浓度外推法确定方法检出限，为0.04~0.6 μg/L；18种酚类化合物的加标回收率为51.7%~117.3%，相对标准偏差为3.1%~7.4%。应用建立的方法分别检测了河流湖泊水、生活用水、生产用水3大类6种不同的水质。检测结果表明，河流湖泊水中酚类化合物所含种类最多，含量最高。研究建立的方法不需要衍生，简化了前处理方法，操作简单，且准确性高，重复性好，可同时检测复杂水体中多种酚类化合物，能显著提高酚类化合物的分析速率。该方法的建立对我国水中酚类化合物残留水平的控制、检测标准的制定和管理措施的采取，都具有重要的理论和现实意义。     

The mass spectra of amino-acid and peptide derivatives—III:. A comparison of the utility of various N-protecting groups

Comparison of the acetyl-, trifluoroacetyl-, benzyloxycarbonyl-, methoxycarbonyl-, ethoxycarbonyl, methylaminocarbonyl, phenylaminocarbonyl-, phthanoyl-, and stearoyl-derivatives of glycylleucylphenylalanine methyl ester has shown that acetyl derivative is the most volatile. The relative abundances of the sequence ions in the mass spectra od these compounds have been determined and compared: the acetyl derivative provides the best combination of volatility and abundance of sequence ions. Evidence is presented to show that the use of acid-catalysed esterification procedure for the chemical modification of peptides prior to mas spectrometric investigation can lead to degraded derivatives.     

张裕XO级白兰地挥发性成分的提取分离与鉴定

建立了一套对白兰地挥发性物质进行预处理的方法,并采用气相色谱-质谱法(GC-MS)较全面地鉴定了白兰地的挥发性成分。实验先采用液-液萃取方法提取张裕XO级白兰地的挥发性成分,然后将酸性成分与碱性和中性成分分离,再采用柱色谱分离手段将其分离为若干个级分并浓缩,采用气相色谱-质谱、标准品比对、保留指数(RI)值比较等方法对分离得到的各级分中的成分进行了鉴定,在白兰地中共鉴定出302种挥发性成分,包括醇30种、醛酮类35种、酸类20种、酯类104种、苯同系物及其衍生物24种、酚类14种、缩醛14种、呋喃类16种、萜烯类22种和其他物质23种。结果表明,采用这套预处理方法能将白兰地的挥发性成分较有效地分组和浓缩。     

Comparison of Phenolic Profile of Balsamic Vinegars Determined Using Liquid and Gas Chromatography Coupled with Mass Spectrometry

Balsamic vinegar is one of the best known and most popular types of vinegar, and it is a rich source of polyphenolic compounds. The quality of balsamic vinegar as well as the content of phenolic substances vary depending on the production method. In the present work, we have developed a method for comprehensive characterization of the content of phenolic compounds in balsamic vinegars based on the combination of gas chromatography (GC) and high-performance liquid chromatography (HPLC) coupled with mass spectrometric detection in single mode (MS) and tandem mode (MS/MS). In total, 14 samples of different types of balsamic vinegar were analyzed without difficulty in sample preparation. The separation conditions and detection parameters of HPLC-MS/MS were optimized and used for the determination of 29 phenolic compounds and 6 phenolic acids. The profile of phenolic compounds was completed by semi-quantitative analysis of volatile organic compounds using GC-MS after optimized headspace solid-phase microextraction. Gallic acid, protocatechuic acid, caffeic acid, and p-coumaric acid have been identified as the major phenolic compounds in balsamic vinegars.     

Asaricin, the main component of Ocotea opifera Mart. essential oil

Investigation of the volatile fraction from the stem bark of Ocotea opifera Mart. led to the isolation and characterization of asaricin, a phenolic derivative with antifungal and insecticidal activity, as the main component, which is described for the first time for the genus Ocotea. The structure has been established by a study of its mono- and bidimensional NMR spectra and mass spectrometry.     

Phenolic characterization of Northeast Portuguese propolis: usual and unusual compounds

In this study, an ethanolic extract from Portuguese propolis was prepared, fractionated by high-performance liquid chromatography, and the identification of the phenolic compounds was done by electrospray mass spectrometry in the negative mode. This technical approach allowed the identification of 37 phenolic compounds, which included not only the typical phenolic acids and flavonoids found in propolis from temperate zones but also several compounds in which its occurrence have never been referred to in the literature. Four of the novel phenolic compounds were methylated and/or esterified or hydroxylated derivatives of common poplar flavonoids, although six peculiar derivatives of pinocembrin/pinobanksin, containing a phenylpropanoic acid derivative moiety in their structure, were also identified. Furthermore, the Portuguese propolis sample was shown to contain a p-coumaric ester derivative dimer.     

The Infestation of Olive Fruits by Bactrocera oleae (Rossi) Modifies the Expression of Key Genes in the Biosynthesis of Volatile and Phenolic Compounds and Alters the Composition of Virgin Olive Oil

Bactrocera oleae, the olive fruit fly, is one of the most important pests affecting the olive fruit, causing serious quantitative and qualitative damage to olive oil production. In this study, the changes induced by B. oleae infestation in the biosynthesis of volatile and phenolic compounds in olive (cvs. Picual, Manzanilla, and Hojiblanca) have been analyzed. Despite cultivar differences, the oils obtained from infested fruits showed a significant increase in the content of certain volatile compounds such as (E)-hex-2-enal, ethanol, ethyl acetate, and β-ocimene and a drastic decrease of the phenolic contents. The impact of those changes on the inferred quality of the oils has been studied. In parallel, the changes induced by the attack of the olive fly on the expression of some key genes in the biosynthesis of volatile and phenolic compounds, such as lipoxygenase, β-glucosidase, and polyphenol oxidase, have been analyzed. The strong induction of a new olive polyphenol oxidase gene (OePPO2) explains the reduction of phenolic content in the oils obtained from infested fruits and suggest the existence of a PPO-mediated oxidative defense system in olives.