MALDI-TOF-MS法对重组人内皮抑素蛋白分子质量测定

肿瘤的生长依赖于血管的生成,新生血管不仅为肿瘤生长提供必需的营养物质,而且为肿瘤细胞扩散提供了重要的途径。1997年哈佛大学的O'Reilly等发现了一种内源性新血管生成抑制因子内皮抑素(Endoscatin),显示出特异抑制激活的血管内皮细胞增殖和肿瘤新血管生成的生物学活性,其抗肿瘤作用具有高效、低毒、无耐药性的优点。目前,内皮抑素的研究引起了国内外广泛的兴趣,在美国已进行以安全性为目的的I期临床实验,国内也有多家公司对内皮抑素进行了抗肿瘤研究并申报一类新药。内皮抑素有望成为医治肿瘤而又没有化疗和放疗的毒副作用的一种新的治疗方法,但是否能作为药物应用于临床,尚需对内皮抑素的结构特点及抑制肿瘤和内皮细胞的作用机制等方面进行许多深入的研究。     

Study on the matrix effect in the determination of selected pharmaceutical residues in seawater by solid-phase extraction and ultra-high-performance liquid chromatography–electrospray ionization low-energy collision-induced dissociation tandem mass spectrometry

Matrix effect is a major problem when trace level pharmaceuticals in seawater were analyzed using solid-phase extraction (SPE) combined with high-performance liquid chromatography–electrospray ionization tandem mass spectrometry (HPLC–ESI–MS–MS). Therefore, efforts should be devoted to diminish matrix effect as much as possible. The present study investigates the matrix effect during the analysis of selected pharmaceutical residues (naproxen, ibuprofen, diclofenac and gemfibrozil) in seawater samples with ultra-high-performance liquid chromatography (UHPLC)–ESI low-energy collision-induced dissociation (CID) MS–MS. Solutions to reduce matrix effect were studied through optimization of SPE procedure and the employment of isotope-labeled analogues. Results showed that 30 mL of deionized water can efficiently diminish matrix effect and satisfactory absolute mean recoveries ranging from 73.5% to 120.5% were obtained in the optimized SPE condition. Isotope-labeled analogues employed as surrogates were found to be efficient to further compensate for matrix effect, with the relative mean recoveries ranging from 85.5% to 110.5%. The optimized method has been successfully applied for the analysis of target pharmaceutical residues in different seawater samples.     

Fluoroquinolone antibiotics in environmental waters: Sample preparation and determination

The aim of this review is to provide a general overview on the analytical methods proposed in the last decade for trace fluoroquinolone (FQ) determination in environmental waters. A large number of studies have been developed on this topic in reason of the importance of their monitoring in the studies of environmental mobility and potential degradation pathways. Every step of the analysis has been carefully considered, with a particular attention to sample preparation, in relationship with the problems involved in the analysis of real matrices. The different strategies to minimise interference from organic matter and to achieve optimal sensitivity, especially important in those samples with lower FQ concentrations, were also highlighted. Results and progress in this field have been described and critically commented. Moreover, a worldwide overview on the presence of FQs in the environmental waters has been reported.     

液体顶空-气相色谱法测定食品接触苯乙烯聚合物中单体及溶剂残留

提出了液体顶空-气相色谱法测定食品接触苯乙烯聚合物中残留单体及溶剂的方法。采用N,N-二甲基乙酰胺溶解聚合物,使其中残留单体及溶剂完全释放,并在优化的工作条件下,以基体匹配校正法绘制工作曲线,有效消除基质效应。7种分析物检出限(3S/N)在0.2～4.1mg.kg-1之间。测得方法的回收率在93.2%～103.2%之间,测定值的相对标准偏差(n=6)在1.1%～5.6%之间。     

Proficiency testing schemes for therapeutics and toxicology

 This report addresses the proposition: current proficiency testing (PT) schemes for therapeutics and toxicology can easily engender complacency. The proposition was based on the premise that there are substantial between-laboratory differences and objectives in the supply of services for the measurement of drugs, as a result of which it is difficult to design PT schemes which adequately cover the requirements of all laboratories. Thus, acceptable performance in a PT scheme may lead participants to consider that they have tested their procedures more rigorously than is the case. Four areas, validity of the PT scheme, PT material, frequency of testing and acceptance criteria are examined. Received: 15 April 2000 · Accepted: 15 April 2000     

Infrared matrix isolation study of the reaction of CrCl2O2 with (CH3)2O and (CH3)2CO

Matrix isolation has been combined with infrared spectroscopy to study the reaction chemistry of CrCl₂O₂ with (CH₃)₂O and (CH₃)₂CO. Very similar results were obtained with twin jet and room temperature merged jet deposition, indicating that the initial product forms on the surface of the matrix during deposition, not in the deposition lines prior to matrix condensation. The initial product in both systems was identified as the 1:1 complex between the two reagents, with a structure in which the oxygen atom of the base donates electron density to the Cr center. A number of perturbed vibrational modes of both subunits were observed; for the bases, these modes were vibrations involving the oxygen atom. Hg arc irradiation of the CrCl₂O₂·O(CH₃)₂ complex led to growth of a secondary product that is tentatively identified as Cl₂CrO(OCH₃)₂. The CrCl₂O₂·OC(CH₃)₂ complex was not photosensitive, and no rearrangements were observed.     

Interlaboratory comparisons and improvements of methods for acid number determination in used motor oils

The results of two interlaboratory comparisons of acid number determinations in used motor oils are discussed. It is shown that the comparability of the measurement results is not as good as that required by known standards for petroleum products. The problem is motor oil contaminants which accumulated during use, and which are the source of a matrix effect in the acid number determination. The standard methods’ drawbacks are analyzed and some improvements are proposed. Repeatability and accuracy of the improved methods are evaluated. Received: 11 December 2001 Accepted: 15 February 2002     

Synthesis and evaluation of stereopure α-trifluoromethyl-malic hydroxamates as inhibitors of matrix metalloproteinases

The total synthesis of trifluoromethyl (Tfm) analogs of known nanomolar matrix metalloproteinases (MMPs) inhibitors has been performed. The synthetic protocol is based on a moderately stereoselective aldol reaction of trifluoropyruvate with an N-acyl-oxazolidin-2-thione for the construction of the core α-Tfm-malic unit. Both the diastereomeric forms of the target α-Tfm-malic hydroxamates showed micromolar inhibitory potency toward MMP-2 and 9, with a substantial drop with respect to the parent unfluorinated compounds.     

Investigation of hydroxyl-mediated spectral interference from easily ionized elements in laser-enhanced ionization spectrometry in the 281–285 nm range

The spectral background from 281 to 285 nm in the laser-enhanced ionization (LEI) spectrum of aqueous samples containing easily ionized elements (EIE) at concentrations similar to those found in blood was investigated. A complex, structured spectral background was observed, which appears in the presence of Na or K, but does not match the spectral signature of either element. The same behavior was also observed for Li. It was established that this background originates from an energy transfer between laser-excited hydroxyl (OH) molecules and ground-state EIEs. The intensity of this spectral feature was found to increase with EIE concentration and applied electrode voltage. This unexpected source of spectral interference may complicate the determination of trace metals by LEI in the presence of EIEs, since it can not be prevented by simply avoiding interference from atomic lines.     

电感耦合等离子体原子发射光谱分析中易电离元素的基体干扰及其抑制的研究

选取铝、铜、镁、钙、铁、锰和锌等7种元素的9条谱线,研究电感耦合等离子体原子发射光谱法对其测定时易电离元素钾、钠的基体干扰。结果表明:易电离元素对待测元素具有较明显的干扰作用,而增大射频发射功率及降低雾化器压力可有效地抑制易电离元素对待测元素的干扰。