小试金富集ICP-AES法同时测定试样中的铂、钯、金

文章报道了用小试金富集ICP AES法同时测定试样中的铂、钯和金 ,将 1 0～ 2 0g试样中的铂、钯、金富集在毫克量的银合粒中 ,制成溶液后用ICP AES法同时测定铂、钯和金。该方法的检出限 (μg·mL-1 )Pt,Pd ,Au分别为 0 0 1 ,0 0 0 5 ,0 0 1 ,相对标准偏差 (RSD ,n =1 0 )分别为 0 1 % ,0 1 2 % ,0 0 9% ,标准回收率均在 97%以上。生产实践表明 ,本方法是一种快速、简便、准确的分析方法 ,已被我们应用于测定样品中的铂 ,钯和金     

Synthesis,spectroscopic characterization (IR, 1H, 13C and 119Sn NMR,electrospray mass spectrometry) and toxicity of new organotin(IV) complexes with N,N′,O‐ and N,N′,S‐scorpionate ligands

New organotin(IV) derivatives containing the anionic ligands bis(3,5‐dimethylpyrazol‐1‐yl)dithioacetate [LCS₂]⁻ and bis(3,5‐dimethylpyrazol‐1‐yl)acetate [LCO₂]⁻ have been synthesized from reaction between (CH₃)₂SnCl₂ and lithium salts of the ligands. Mononuclear complexes of the type {[LCX₂](CH₃)₂SnCl} (X = S or O) have been obtained and fully characterized by elemental analyses and FT‐IR in the solid state and by NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopy, conductivity measurements and electrospray ionization mass spectrometry in solution. The acute toxicity of new organotin(IV) derivatives on rat was studied, comparing their effect with those of dimethyltin chloride (CH₃)₂SnCl₂. The comparison of LD₅₀ of organotin(IV) complexes and (CH₃)₂SnCl₂ administered intraperitoneally, as a single dose, evaluated in vivo on rats, showed that toxicity decreases as follows: (CH₃)₂SnCl₂ > LCO₂ > LCS₂. The effect of these organotin(IV) complexes on DNA was evaluated in vitro and in vivo on rats treated with different doses of these compounds (1/20 LD₅₀ and 1/100 LD₅₀). The lymphocyte DNA status was assessed by the comet assay, a rapid and sensitive single‐cell electrophoresis technique, used to detect primary DNA damage in individual cells. After 36 h from the start of treatment the two new organotin(IV) derivatives induced a significant rise in comet assay parameters, indicating an increasing presence of damaged DNA. Copyright © 2005 John Wiley & Sons, Ltd.     

Sensitivity enhancement and matrix effect evaluation during summation of multiple transition pairs—case studies of clopidogrel and ramiprilat

Sensitivity enhancement via summation of multiple MRM transition pairs is gaining popularity in tandem mass spectrometric assays. Numerous validation experiments describing the assays for two model substrates, clopidogrel and ramiprilat, were performed. The quantitation of clopidogrel was achieved by the summation of transition pairs m/z 322.2 to m/z 212.0 and m/z 322.2 to m/z 184.0, while that of ramiprilat was achieved by the summation of transition pairs m/z 389.2 to m/z 206.1 and m/z 389.2 to m/z156.1. The use of summation approach achieved sensitivities of >2 fold for both compounds as compared with the reported single MRM transition pair assays. The validation experiments addressed some important assay development issues, such as: (a) lack of impact of matrix effect; (b) unequivocal verification of the percentage contribution of each MRM transition pair towards sensitivity; (c) sensitivity enhancement factor achieved by summation approach of MRM transition pairs; and (d) accurate prediction of quality control samples using summation approach vs a single MRM transition pair. In summary, the appropriateness of using two MRM transition pairs for quantitation was demonstrated for both clopidogrel and ramiprilat. Additionally, pharmacokinetic application of the MRM transition pair assays using a summation approach was established for the two compounds. Copyright © 2009 John Wiley & Sons, Ltd.     

In vitro bioassays for the study of endocrine-disrupting food additives and contaminants

Endocrine-disrupting chemicals (EDCs) are capable of interfering with normal hormone homeostasis by acting on several targets and through a wide variety of mechanisms. Unwanted exposure to EDCs can lead to a wide spectrum of adverse health effects, especially when exposure is during critical windows of development. Feed and food are considered to be among the main routes of inadvertent exposure to EDCs, so there is an important need for efficient detection of EDCs in these matrices.We describe in vitro bioassays that can complement current analytical chemistry in order to detect unwanted EDCs and describe their action, emphasizing assays that can measure effects on nuclear receptor signaling or hormone production. We outline both validated and unvalidated in vitro assays currently available in the scientific community for detecting and studying the effects of EDCs, and discuss their possible role in the food-safety context. We conclude by identifying gaps in the current battery of in vitro assays available for EDCs and suggest future possibilities for development and validation.     

Dipyrrylmetheneboron Difluorides as Labels in Two-Photon Excited Fluorometry. Part II–Nucleic Acid Hybridization Assays

Five two-photon excitable dipyrrylmetheneboron difluoride labels (dipyrrylmethene-BF₂ labels) with fluorescence emission maximum between 530 and 590 nm, and a frequently used rhodamine label, TAMRA, were conjugated to aminomodified oligonucleotides. The performance of the labeled oligonucleotides was studied in a separation-free nucleic acid hybridization assay using ArcDia^™ TPX bioaffinity assay technology. The results show that oligonucleotide conjugates of dipyrrylmethene-BF₂ labels provide higher two-photon excited fluorescence yield and better assay sensitivity than corresponding TAMRA conjugate. The effect of conjugation on photophysical properties of the labels and performance of the labeled oligonucleotides in separation-free hybridization assay is discussed.     

Profiling of generic anti-phosphopeptide antibodies and kinases with peptide microarrays using radioactive and fluorescence-based assays

Kinases represent one of the largest enzyme families and key regulatory proteins in the cell. Only a small subset of these enzymes has been characterised so far. We have prepared different types of phosphopeptide and peptide microarrays displaying peptides deduced from annotated human phosphorylation sites and cytoplasmic domains of all annotated human membrane proteins. This approach was enabled by fully-automated high throughput micro-scale synthesis of peptides by the SPOT technology combined with chemo-selective immobilisation on modified glass slides. The phosphopeptide microarrays displaying 2923 peptides in total have been used for the characterisation of commercially available generic anti-phosphopeptide antibodies. This enabled us to detect Abl kinase activity on a microarray with anti-phosphotyrosine antibodies yielding results comparable to those obtained from a radioactive assay. More than 13 000 peptides deposited on six glass slides were used to profile casein kinase 2 (CK2) using a radioactive assay, since no generic antibody for the reliable detection of serine or threonine phosphorylation could be identified. All previously identified substrates were detected in the microarray experiment. In order to confirm whether substrates on the microarray are substrates in solution phase assays, more than 700 peptides were synthesised and tested with CK2 in a solution phase assay. All substrates identified in the solution phase assay were also detected on the microarray.     

Defining the antigenic structure of human GM-CSF and its implications for receptor interaction and therapeutic treatments

Three epitopes of human Granulocyte-Macrophage Colony-Stimulating Factor (hGM-CSF) recognised by neutralising and non-neutralising monoclonal antibodies (mAbs) were characterised using competitive binding assays, dissociation constant measurements with glycosylated and non-glycosylated rhGM-CSF, bioactivity inhibition studies, and synthetic peptide arrays. Based on the first approach, two different binding sites were identified: an area referred to as A, recognised by mAbs M1B8 and CC5B5, and an area referred to as B, recognised by mAbs CC1H7 and CC3C12. These binding sites on hGM-CSF were accurately delineated using cytokine-derived overlapping peptide scans and combinatorial hexapeptide libraries prepared by SPOT synthesis on cellulose membranes. We assigned the identical linear epitope A₁P₂A₃R₄ to both non-neutralising mAbs CC1H7 and CC3C12. The conformational epitopes A₁₈E₂₁R₂₃R₂₄F₁₁₉ and R₂₃E₂₁N₁₇W₁₃ recognised by mAb CC5B5, and P₁₁₈F₁₁₉EW₁₃E₁₄ recognised by mAb M1B8, were delineated by dual-positional scanning and subsequent iterative searches with two interrogating positions. Competitive binding assays with mAbs M1B8 and CC5B5 revealed the overlapping nature of the cytokine recognition. However, peptide library screening confirmed their binding to different epitopes of which the essential amino acids were found very closely located on the native protein surface. Inhibition of hGM-CSF biological activity by these mAbs demonstrated that these epitopes are located within or very near the receptor binding site of hGM-CSF. Finally, this work supports the importance of residues from helix A and residues from the C-terminal region of the cytokine, composing a common area that is indispensable for the cytokine's biological activity.     

Identification and assay of wild-type and modified nucleoside mixtures by turbo ionspray ionization tandem mass spectrometry

A method is presented which allows the identification and assay of a nucleoside in the presence of other analogues and homologues. The method is based on the conventional multiple reaction monitoring approach performed on the [M + H]+ ions of wild-type and modified nucleosides produced by the turbo ionspray ionization method on a triple-quadrupole mass spectrometer. The accuracy of the quantitative determination relies on the evaluation of a response factor rho, which takes into account the kinetics of dissociation of the parent ions into the protonated [B + 2H]+ nucleobase ions. The evaluation of the absolute concentration of each analyte in the examined mixture does not require any previous chromatographic separation.     

Estimating vaccine coverage by using computer algebra

Email: altmannd{at}rki.deEmail: altmann{at}mathematik.hu-berlin.de The approach of N Gay for estimating the coverage of a multivalentvaccine from antibody prevalence data in certain age cohortsis complemented by using computer aided elimination theory ofvariables. Hereby, Gay's usage of numerical approximation canbe replaced by exact formulae which are surprisingly nice, too.     

Development of Nanosensors and Bioprobes

We describe the development and application of nanosensors having bioreceptor probes for bioanalysis. The nanoprobes were fabricated with optical fibers pulled down to tips having distal end sizes of approximately 30–60nm. The use of two different types of receptors was investigated. Fiberoptic nanoprobes were covalently bound either with bioreceptors, such as antibodies, or with other receptors, such as cyclodextrins that are selective for the size and chemical structure of the analyte molecules. Theoretical calculations were performed to model the binding of beta-cyclodextrin with pyrene and 5,6-benzoquinoline, and to illustrate the possibility of comparing experimental data with theoretical data. The antibody-based nanoprobe was used for in situ measurements of benzopyrene tetrol in single cells. The performance of the nanosensor is illustrated by intracellular measurements performed on a rat liver epithelial cell line (Clone 9) used as the model cell system. The usefulness and potential of these nanotechnology-based biosensors in biological research and applications are discussed.