高效液相色谱法测定面粉中苯磺酰胺

建立了高效液相色谱测定面粉中苯磺酰胺的定量检测方法。样品经甲醇提取、浓缩、N2吹至近干并定溶后,经高效液相色谱检测。     

磷脂的高效液相色谱分析

天然磷脂是含磷酸的类脂化合物,广泛存在于植物、动物及微生物体中,在工业生产、食品科学、医药学、生命科学等研究方面都有重要的应用。磷脂的研究手段多样,高效液相色谱在磷脂的分离、检测方面具有优势。本文结合近年来国内外高效液相色谱分离磷脂的研究报道,对高效液相色谱分离、检测磷脂的方法进行了分类、评价。     

六价铬检测进展研究

针对皮革中六价铬的危害及其检测方法简要介绍,对当前六价铬检测的分光光度计法、液相色谱一质谱联用仪法、液相色谱一电感耦合等离子质谱法等加以分析,并对各个方法的优缺点予以评价,以期为消除国际皮革贸易的绿色壁垒,加强对皮革制品中的六价铬的检测研究,建立灵敏度高、检出限低、通用性强的检测方法奠定基础。     

氯吡脲残留检测技术进展及趋势

氯吡脲是一种较新的人工合成苯脲类细胞分裂素,近年来其作为高效植物生长调节剂被广泛用于增大水果尺寸,尤其是猕猴桃和葡萄。为保证食品安全,需要采用灵敏准确的检测方法来对氯吡脲残留进行定量检测,目前国内外报道的氯吡脲检测方法主要为高效液相色谱-紫外检测法和高效液相色谱-质谱法。结合适当的样品前处理手段,高效液相色谱-紫外检测法和高效液相色谱-质谱法均能满足不同国家针对不同作物制定的氯吡脲最大残留水平(MRL)10～100μg/kg的定量检测要求。随着液相色谱-串联质谱的普及,氯吡脲残留分析趋向于采用前处理更加简化的高通量例行检测方法。     

色谱分析法在斑蝥黄测定中的研究进展

本文从斑蝥黄的稳定性、样品的前处理技术和检测方法等方面,着重阐述了色谱技术在斑蝥黄测定中的应用,包括高效液相色谱法、高效液相色谱-串联质谱法。     

肉制品中山梨酸、苯甲酸的检测方法

当前,GB/T5009.29-2003<食品中山梨酸、苯甲酸的测定>中关于山梨酸、苯甲酸的液相色谱检验方法,缺少对固体样品的提取方式,笔者根据山梨酸、苯甲酸的化学性质,研究出肉制品中山梨酸、苯甲酸高效液相色谱的检测方法.     

猪肝中克伦特罗的测定─反相高效液相色谱法

本文介绍了一种简单、快速测定猪肝中克伦特罗的液相色谱检测方法,色谱保留、分离均优于C18分离体系,准确性和精密度满足检测要求需要。     

液相色谱质谱联用仪的使用和保养

液相色谱质谱联用仪因其分析范围广、分离能力强、检测限低、分析快速等优点在生物、医药、化学、化工、环境等学科得到了广泛的应用。本单介绍了液相色谱质谱联用仪的原理、种类及应用范围,着重介绍了液相色谱质谱联用仪在使用及维护保养的要点和注意事项,以及校准仪器的方法。     

液相色谱技术在农药残留检测中的应用

液相色谱技术在农药残留检测中有着重要的应用,本文从液相色谱法的概念及特点入手,分析了液相色谱技术在水质及食物中检测农药残留的应用现状。     

浅谈液相色谱仪常见故障的检查与排除

针对在液相色谱使用中出现的常见问题,文章从液相色谱工作输液、进样和检测这三大系统及构成这三个系统部件的结构和功能这几个方面介绍了液相色谱仪的故障排除解决方法。     

AAS、ICP-AES和HG-AFS在水质检测中的比较

对水质检测中测定金属元素经常使用的三种分析方法:原子吸收法(火焰法和石墨炉法)、电感耦合等离子体发射光谱法和氢化物发生-原子荧光光谱法。光谱的主要优缺点进行了比较。重点比较的内容有:水样的预处理步骤、干扰因素(包括光谱干扰、化学干扰、电离干扰)、各元素的检出限、线性范围、精密度和同时测定多元素能力的比较。     

Enhanced ionization of phosphorylated peptides during MALDI TOF mass spectrometry

Although alpha-cyano-4-hydroxycinnamic acid functions as an excellent matrix for the analysis of most peptides using matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectrometry, the ionization of phosphorylated peptides is usually suppressed by nonphosphorylated peptides. As an alternative matrix, 2',4',6'-trihydroxyacetophenone (THAP) with diammonium citrate was found to overcome this problem for the MALDI TOF mass spectrometric analysis of proteolytic digests of phosphorylated proteins. Specifically, the abundances of phosphorylated peptides in tryptic digests of bovine beta-casein and protein kinase C (PKC)-treated mouse cardiac troponin I were enhanced more than 10-fold using THAP during positive ion MALDI TOF mass spectrometry. The protonated molecules of phosphorylated peptides were sufficiently abundant that postsource decay TOF mass spectrometry was used to confirm the number of phosphate groups in each peptide. Finally, tryptic digestion followed by analysis using MALDI TOF mass spectrometry with THAP as the matrix facilitated the identification of a unique phosphorylation site in PKC-treated troponin I.     

基于SPME-GC-MS分析卷烟包装材料挥发性气体的研究

目的 建立一种高效且准确的分析测试方法,快速检测卷烟包装材料中挥发性气体的类别和含量.方法 基于气相色谱-质谱联用(GC-MS),比较传统顶空-气相色谱-质谱联用(HS-GC-MS)和固相微萃取-气相色谱-质谱联用(SPME-GC-MS)的检测效果,并对SPME-GC-MS检测的各项参数进行优化.结果 确定了SPME-GC-MS定性、定量分析卷烟材料气味的最优分析条件,并对印刷工艺较为复杂的盒包卷烟包装材料进行了高效、准确的检测.结论 建立的SPME-GC-MS方法可以对盒包卷烟包装材料挥发性气体的异味进行定性和定量分析,为盒包材料的品质评价和印刷过程中异味的检测提供了新的策略.     

Accuracy of field spectrometry in estimating 137Cs contamination in high altitude alpine soils

In situ gamma ray spectrometry is an attractive method for providing information on the concentrations of radionuclides in the soil. This method requires separate knowledge of the soil density and of the radioactivity distribution relative to soil depth. In-field gamma spectrometry measurements were performed together with sampling of the soil at the same site for subsequent gamma spectrometry analysis in the laboratory. Results of 137Cs concentration were compared in order to: (i) verify the effectiveness of in situ gamma spectrometry in averaging local inhomogeneties in the soil; and (ii) quantify the sensitivity of the gamma ray spectrometry soil radioactivity evaluation with respect to the variability of the depth profiles obtained from a single site sampling. The site of study is a high altitude pasture, in the Alpine environment.     

Preliminary evaluation of micro-Raman spectrometry for the characterization of individual aerosol particles

Raman spectrometry has been used to determine the graphitic C content and to estimate particle size and disordered character of the C in aerosol particulate matter collected on filters, with sample spot sizes on the order of 100 microm being analyzed. Individual analysis of particulate matter with aerodynamic diameters less than 10 microm has therefore not been considered. In this investigation, various size fractions of aerosol particulate matter originating from both indoor and outdoor sources were collected by means of impactors or passive dry deposition on different types of substrate and analyzed by means of micro-Raman spectrometry with spot sizes ranging from 1-5 microm. The aim was to investigate the possible application of micro-Raman spectrometry to the molecular characterization of individual aerosol particles and to assess the applicability of the various substrates in such an analysis. It was demonstrated that the molecular characterization of most inorganic particles is trivial, but organic and heterogeneous conglomerates proved to be more challenging. Spectral contributions of the substrates, currently favored for individual particle analysis, were significant. Results obtained from micro Raman spectrometry can certainly add valuable molecular information on individual aerosol particles as small as 1 microm aerodynamic diameter.     

Colloidal graphite-assisted laser desorption/ionization mass spectrometry and MSn of small molecules. 1. Imaging of cerebrosides directly from rat brain tissue

Graphite-assisted laser desorption/ionization (GALDI) mass spectrometry (MS) was investigated for analysis of cerebrosides in a complex total brain lipid extract. Conventional MALDI MS and GALDI MS were compared regarding lipid analysis by using high-vacuum (HV, <10-6 Torr) LDI time-of-flight mass spectrometry and intermediate-pressure (IP, 0.17 Torr) linear ion trap mass spectrometry. Cerebrosides were not detected or detected with low sensitivity in MALDI MS because of other dominant phospholipids. By using GALDI, cerebrosides were detected as intense mass peaks without prior separation from other lipid species while mass peaks corresponding to phosphatidylcholines (PCs) were weak. The signal increase for cerebrosides and the signal decrease for PCs in GALDI MS were more significant in HV than in IP. MSn experiments of precursor ions corresponding to cerebrosides and PCs in brain lipid extract were performed to identify the detected species and distinguish isobaric ions. Twenty-two cerebroside species were detected by GALDI whereas eight cerebroside species were detected by MALDI. Sulfatides in brain lipid extract were also easily detected by GALDI MS in the negative ion mode. By forming a colloidal graphite thin film on rat brain tissue, direct lipid profiling by imaging mass spectrometry (IMS) was performed. Chemically selective images for cerebrosides and sulfatides were successfully obtained. Imaging tandem mass spectrometry (IMS/MS) was performed to generate images of specific product ions from isobaric species.     

Single-protein nanomechanical mass spectrometry in real time

Nanoelectromechanical systems (NEMS) resonators can detect mass with exceptional sensitivity. Previously, mass spectra from several hundred adsorption events were assembled in NEMS-based mass spectrometry using statistical analysis. Here, we report the first realization of single-molecule NEMS-based mass spectrometry in real time. As each molecule in the sample adsorbs on the resonator, its mass and position of adsorption are determined by continuously tracking two driven vibrational modes of the device. We demonstrate the potential of multimode NEMS-based mass spectrometry by analysing IgM antibody complexes in real time. NEMS-based mass spectrometry is a unique and promising new form of mass spectrometry: it can resolve neutral species, provide a resolving power that increases markedly for very large masses, and allow the acquisition of spectra, molecule-by-molecule, in real time.     

Preparation, separation, and conformational analysis of differentially sulfated heparin octasaccharide isomers using ion mobility mass spectrometry

Heparin is a linear sulfated polysaccharide widely used in medicine because of its anticoagulant properties. The various sulfation and/or acetylation patterns on heparin impart different degrees of conformational change around the glycosidic bonds and subsequently alter its function as an anticoagulant, anticancer, or antiviral drug. Characterization of these structures is important for eventual elucidation of its function but presents itself as an analytical challenge due to the inherent heterogeneity of the carbohydrates. Heparin octasaccharide structural isomers of various sulfation patterns were investigated using ion mobility mass spectrometry (IMMS). In addition to distinguishing the isomers, we report the preparation and tandem mass spectrometry analysis for multiple sulfated or acetylated oligosaccharides. Herein, our data indicate that heparin octasaccharide isomers were separated on the basis of their structural conformations in the ion mobility cell. Subsequent to this separation, isomers were further distinguished using product ions resulting from tandem mass spectrometry. Overall, IMMS analysis was used to successfully characterize and separate individual isomers and subsequently measure their conformations.     

Determination of 232Th by neutron activation analysis using isotope-related ki factors

Neutron activation analysis was applied to determine the 232Th activity in different matrices. Since in nature thorium consists of almost 100% of the long-lived 232Th, the instrumental trace element analysis method of neutron activation analysis can be applied to determine the thorium content in a sample. which can then be converted into the corresponding specitic activity. For the analysis about 100 mg of the sample was irradiated at a thermal neutron flux of phi(th) = 8 x 10(13) n.cm(-2) x s(-1). After irradiation the activity of the indicator nuclid 232Pa--produced by the (n,gamma) reaction--was measured by gamma spectrometry. The content of thorium was calculated using the activation equation and the isotope-related ki constant. Finally, the concentration of thorium in the sample was converted into the specific activity. The activities of 232Th measured by applying neutron activation analysis in different samples were compared with the results found by a spectrometry and gamma spectrometry for the daughter nuclides 228Ac and 224Ra.     

Multiphoton ionization mass spectrometry of chlorophenols as indicators for dioxins

Mono-, di- and trichlorophenols were measured using resonance-enhanced multiphoton ionization mass spectrometry (MPI-MS) combined with supersonic jet (SSJ) or effusive molecular beam (EMB) spectrometry. All mono- and dichlorophenols, except 2,6-dichlorophenol, provided sharp and structured MPI spectra for the S1 <-- S0 transition. Selectivity and sensitivity were both enhanced when SSJ spectrometry was used, compared with EMB spectrometry, because of a narrower linewidth in the MPI spectrum, given by molecular cooling by supersonic jet expansion. The ionization efficiency decreased with increasing number of chlorine substituents for the chlorophenols, since they have shorter excited-state lifetimes and require three photons for ionization. Some of the chlorophenols, which are toxic themselves, have the potential for use as indicators for analysis of polychlorinated dibenzo-p-dioxin/dibenzofurans in flue gases emitted from an incinerator.