薄层色谱扫描法测定塑料食品袋中酞酸酯的含量

建立了采用薄层色谱扫描测定塑料食品袋中4种酞酸酯(酞酸二甲酯(DMP)、酞酸二乙酯(DEP)、酞酸二丁酯(DBP)和酞酸二(2-乙基己基)酯(DEHP))的方法。经粉碎的样品先用乙醇浸泡24 h,然后超声提取,经0.45 μm滤膜过滤。点样在以丙酮处理过的硅胶G板上,以乙酸乙酯-无水乙醚-异辛烷(体积比为1∶4∶15)为展开剂展开,以双波长反射吸收飞点扫描测定(λS=275 nm,λR=340 nm),外标法定量。该法的线性关系较好,DMP、DEP、DBP和DEHP的检出限分别为2.1,2.4,3.4和4.0 ng,混合标准品在同一薄层板上的峰面积的相对标准偏差（RSD）为2.8%～3.5%,4种酞酸酯的样品加标回收率为78.58%～111.04%。该方法样品用量少,前处理简单,分离效果好,可用于塑料袋中4种酞酸酯的同时测定。经与气相色谱法的分析结果比较,两种方法对实际样品的分析结果接近。     

Organic Compounds in High Alpine Snow

Abstract

Snow samples were taken in June 1995 at the Sonnblick Observatory located at the top of Mt. Sonn-blick (3106 m a.s.l.) in the main ridge of the Austrian Alps, as part of the project “Organic Aerosol Scavenging”. The main interest focused on the determination of aliphatic compounds and phenols. First the method for the extraction of the organic compounds was developed using standard samples prepared in the lab. The preconcentration of the samples was performed by liquid-liquid extraction with hexane and hexane/diethylether respectively. To characterize the analytical procedure, the efficiency of the extraction procedure, the reproducibility of the overall method and the detection limits were determined. Values for the recovery of the extraction method range from 57% (fatty acids) to 95% (aliphatic alcohols). Reproducibility was found to be between 3-5%, except for the fatty acids which gave a value of 16%. Detection limits were calculated for the various substances and are between 5μg/l (phenols) and 30μg/l (fatty acids). The analysis of the eight snow samples were performed using a GC-MS-FID system. The following compounds were identified as major compounds in the snow samples: 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol, 2-isobutyl-4-methoxy-phenol, diisobutylphenol and dibutylphthalate. The aliphatic alcohols are of biogenic origin and are present in a concentration range from 30 to 115 μg/l melted snow. The phenols show concentrations between 5 and 30 μg/l and the phthalates range up to 40 μg/l.     

Differential Contribution of Albumin and Lipids to the Hydrophobic Extraction of Bis-(2-ethylhexyl) Phthalate from Hemodialysis Tubing by Human Serum: Analysis by Gas Chromatography - Stable Isotope Dilution Mass Spectrometry

Abstract

A method is presented which allows quantitative assignment of hydrophobic human serum components to the extraction of bis-(2-ethylhexyl) phthalate (DEHP) from medical tubing. Under optimized conditions (sample pH 5.5; fluid-fluid extraction with ethyl acetate + tert-butyl methyl ether 1 + 1 v/v; DEHP-ring-D4 as internal standard with ratios of endogenous (m/z = 149) and added deuterated DEHP (m/z = 153) adjusted to around 1.0; equilibration of added internal standard with the hydrophobic sample for 24 hours), a high precision can be achieved with an intra-assay coefficient of variation of 1.5% (n = 7) for sample DEHP quantification. Phthalate migration from hemodialysis tubing was quantified by use of a peristaltic pump and recirculation (200 minutes) of serum with different degrces of hypertriglyceridemia (range from 2.26 to 14.5 g/L) or solutions of human albumin (10 to 50 g/L). Only DEHP, but no other phthalates are detected in the extracts. There exist linear relations between DEHP extraction and triglyceride content (increase by 1.01 μg DEHP/g tubing material per g triglyceride/L serum) as well as between DEHP extraction and albumin content (0.59 μg DEHP/g tubing material per g albumin/L). Under physiological conditions, the total amount of albumin extracts 17.7-fold more DEHP than the total triglyceride amount in human serum. The suitability of the proposed method as a candidate reference method as well as consequences for dyslipidemic and hypalbuminemic patients on hemodialysis schemes are discussed.     

A Facile Synthesis of N γ-Glycosyl Asparagine Conjugates and Short N-Linked Glycopeptides

Both free and protected glycosyl azides were efficiently coupled to the side chain of aspartate by the Staudinger reaction for the synthesis of N ^γ-glycosyl asparagine conjugates and short N-linked glycopeptides that can be employed to construct complex N-linked glycopeptides. In the process, a facile two-step protocol was developed for free glycosyl azide synthesis, which includes reported direct transformation of free oligosaccharides into glycosyl amines through reaction with ammonium bicarbonate and then stereospecific diazo transfer reaction to convert glycosyl amines to glycosyl azides.     

Protecting Group Manipulations on Glycosyl Phosphate Triesters

Glucosyl and mannosyl phosphate triester building blocks were differentially protected by protecting group manipulations on competent glycosyl donors. Dibutyl 3,4‐di‐O‐benzyl‐6‐O‐(fluorenylmethoxycarbonyl)‐2‐O‐pivaloyl‐β‐D‐glucopyranoside phosphate, not accessible by other methods, was prepared this way.     

Synthesis of unnatural N-glycosyl α-amino acids via Petasis reaction

A convenient and efficient protocol for the synthesis of unnatural N-glycosyl a-amino acids was developed.Condensation of 1,3,4,6-tetra-O-actyl-β-D-glucosamine hydrochloride,alkenyl boronic acid,and glyoxylic acid was achieved in CH_2C1_2 to give the derivatives of 2-(N-glycosyl)aminobut-3-enoic acid which may find applications in glycobiology research and medicinal chemistry.     

Identification of Endocrine Disrupting Chemicals using a Virus‐Based Colorimetric Sensor

A simple and portable colorimetric sensor based on M13 bacteriophage (phage) was devised to identify a class of endocrine disrupting chemicals, including benzene, phthalate, and chlorobenzene derivatives. Arrays of structurally and genetically modified M13 bacteriophage were fabricated so as to produce a biomimetic colorimetric sensor, and color changes in the phage arrays in response to several benzene derivatives were characterized. The sensor was also used to classify phthalate and chlorobenzene derivatives as representatives of endocrine disrupting chemicals. The characteristic color patterns obtained on exposure to various benzene derivatives enabled similar chemical structures in the vapor phase to be classified. Our sensing approach based on the use of a genetically surface modified M13 bacteriophage offers a promising platform for portable, simple environmental monitors that could be extended for use in numerous application areas, including food monitoring, security monitoring, explosive risk assessment, and point of care testing.     

Creation of 3,4-bis-triazolocoumarin-sugar conjugates via flourogenic dual click chemistry and their quenching specificity with silver(I) in aqueous media

Fluorogenic click chemistry has recently emerged as an ingenious and powerful tool toward numerous biochemical purposes. We describe herein the use of dual click chemistry toward the fluorescence restoration of a fluorogenic coumarin on epimeric dipropargyl sugar scaffolds and their practical utility in selective metal ion detection. The dual click reactions were smoothly proceeded under microwave irradiation between silylated 3,4-di-O-propynyl gluco- or galactoside and 3-azidocoumarin, forming fluorescently reactivated bis-triazolocoumarins on sugar templates. Subsequent desilylation resulted in the OH-glycosides with desired water solubility. The following photochemical study disclosed that their fluorescence could be uniquely quenched by silver(I) in aqueous media with very minor responses to the addition of other metal ions. This research would presumably prompt the efficient creation of water soluble and potentially low toxic chemosensors via the fluorogenic dual click chemistry in using the universally existent sugars as the central scaffold.     

Synthesis of α-S-galactosylceramides with a truncated sphingoid chain

We present here a convenient synthesis of the truncated sphingoid iodide 15 from d-galactose, in which Mitsunobu reaction was utilized to retrieve successfully an unwanted intermediate, thereby increasing greatly the synthetic efficiency. Subsequent reaction of 15 with the pre-prepared α-galactosyl thiol 16 led smoothly to the desired thioglycoside 17 in good yield, from which the catabolically stable thioglycoside analogs of OCH 4 and 22 were synthesized.     

悬浮固化分散液液微萃取-高效液相色谱法测定水体中邻苯二甲酸酯

建立了悬浮固化分散液液微萃取（SFO-DLLME）结合高效液相色谱（HPLC）快速测定水样中6种邻苯二甲酸酯（PAEs）的分析方法。通过对影响萃取效率因素的优化,确定了最佳萃取条件：十二烷醇萃取剂20 μL、萃取温度60℃、离子强度20 g/L、萃取时间1 min。6种PAEs在2~2000 μg/L范围内呈良好的线性关系,相关系数（r）为0.9995~0.9999,检出限（S/N=3）为0.3~0.6 μg/L。对自来水、湖水、江水、污水、海水、市售塑料瓶装纯净水和矿泉水进行测定,能检测到部分PAEs。对加标水样进行回收率试验（10、100和1000 μg/L）,6种PAEs的回收率为84.9%~94.5%,相对标准偏差为4.1%~6.8%（n=5）。该法环保、简单,可用于实际水样中6种PAEs的检测分析。