液相色谱-同位素稀释串联质谱法测定动物源性食品中硝基呋喃类代谢物残留

加入同位素标记物的动物源性样品(龙虾、肠衣),在酸性条件下用2-硝基苯甲醛,使样品中呋喃唑酮、呋喃西林、呋喃它酮、呋喃妥因实现衍生。经乙酸乙酯提取浓缩、用甲醇水溶液溶解过滤后,滤液用液相色谱-串联质谱定量。在0.5,1.0和2.0μg/kg3个浓度水平上进行添加回收试验,回收率为80.1％～92.2％,检出限(LOQ)...     

一种蛋白同化激素新药的成分分析及其尿样监控

利用红外光谱、核磁共振氢谱、紫外光谱以及质谱等表征手段对一种新型蛋白同化激素(AAS)口服药物的主成分进行了研究和鉴定,推定主成分为甲基-1-睾酮(methyl-1-testosterone, M1T, 17β-hydroxy-17α-methyl-5α-androst-1-en-3-one)。在此基础上,建立了M1T的气相色谱-质谱联用检测方法。方法的检出限（信噪比（S/N)为3)为2 ng/mL,定量限（S/N=10）为10 ng/mL;7次平行测定前处理后的加内标尿样的相对标准偏差为9.8%。用该方法测定了该药物在尿样中的排泄曲线。该方法的建立为AAS新药的发现、检测和监控做了很有意义的基础研究工作。     

电泳和质谱技术研究4种胰脏铁蛋白的亚基类型和等电点特性

采用电泳和质谱技术对所制备的鸡、鸭、牛和猪胰脏铁蛋白的亚基类型和等电点特性进行了研究。采用天然聚丙烯酰胺凝胶电泳(PAGE)技术研究的结果表明,上述4种铁蛋白呈现不同的迁移率,据此可知鸡胰铁蛋白的相对分子质量(Mr)>鸭胰铁蛋白的Mr>黄牛胰铁蛋白的Mr>猪胰铁蛋白的Mr,而且均大于马脾铁蛋白(HSF)的Mr。采用十二烷基硫酸钠(SDS)-PAGE技术研究的结果表明,上述4种铁蛋白均由H(heavy chain)和L(light chain)类型的亚基组成,但H和L亚基的相对数量（即H/L亚基数量的比值）有差别。采用肽指纹图谱技术分别鉴定各铁蛋白的H和L亚基。选用变性等电聚焦方法研究发现,上述4种铁蛋白分别由3～6种不同等电点的亚基聚合体组成,说明铁蛋白的H和L亚基之间呈现复杂的相互作用和不同的聚合体。不同陆生动物胰脏铁蛋白亚基之间相互作用的强度和聚合态存在着差异,这一差异特性可能与调控铁蛋白释放铁的速率有关,也与动物对铁的需求和铁解毒速率有关。     

南北五味子荧光光谱差异的原因

建立了用荧光法快速鉴别五味子和部分含五味子制剂中五味子是属于北五味子还是南五味子的方法,探明了南北五味子荧光光谱差异的主要原因。研究了五味子的五种活性成分五味子醇甲、五味子酯甲、五味子甲素、五味子乙素和安五脂素的荧光性质和五味子以及护肝片乙醇提取液的荧光光谱,并用高效液相色谱测定了供试品五种活性成分的含量。研究表明：发光效率按安五脂素、五味子乙素、五味子甲素和五味子醇甲依次减弱,五味子酯甲不具有荧光性;北五味子的主要荧光物质为五味子乙素,而南五味子的主要荧光物质是安五脂素,它们是导致南北五味子荧光光谱差异的主要原因。用荧光法鉴别南北五味子具有简单、快速和灵敏的特点     

Genetic individualization of <Emphasis Type="Italic">Cannabis sativa</Emphasis> by a short tandem repeat multiplex system

Cannabis sativa is the most frequently used of all illicit drugs in the USA. Cannabis has been used throughout history for its stems in the production of hemp fiber, seed for oil and food, and buds and leaves as a psychoactive drug. Short tandem repeats (STRs) were chosen as molecular markers owing to their distinct advantages over other genetic methods. STRs are codominant, can be standardized such that reproducibility between laboratories can be easily achieved, have a high discrimination power, and can be multiplexed. In this study, six STR markers previously described for C. sativa were multiplexed into one reaction. The multiplex reaction was able to individualize 98 cannabis samples (14 hemp and 84 marijuana, authenticated as originating from 33 of the 50 states of the USA) and detect 29 alleles averaging 4.8 alleles per loci. The data did not relate the samples from the same state to each other. This is the first study to report a single-reaction sixplex and apply it to the analysis of almost 100 cannabis samples of known geographic origin. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Use of Fourier transform infrared spectroscopy and chemometrics to discriminate clinical isolates of bacteria of the Burkholderia cepacia complex from different species and ribopatterns

A methodology for the discrimination of Burkholderia cepacia complex (Bcc) clinical isolates at the species level and at the ribopattern level using Fourier transform infrared (FTIR) spectroscopy and chemometrics analysis was assessed in this study. Different Bcc sequential isolates collected at the Santa Maria Hospital (HSM), in Portugal, from clinically infected cystic fibrosis (CF) patients were previously classified by established molecular methods at the species level and differentiated at the strain level, based on their ribopatterns. A set of 185 of these isolates, representing four different Bcc species (Burkholderia cepacia, Burkholderia cenocepacia (recA lineages III-A and III-B), Burkholderia multivorans and Burkholderia stabilis), was analyzed by FTIR and results were processed with chemometric methods. Ten reference strains of these species were used to test the FTIR method. The discrimination at the species level led to misclassification error rates of 10% and 32% for the HSM isolates and reference strains, respectively, clearly indicating that the FTIR classification method was unable to generalize results for the reference strains. Infrared spectra of HSM isolates were further analyzed in terms of the discrimination according to the ribopattern. Results showed misclassification error rates of 4%, 2%, and 8% for B. cepacia, B. cenocepacia III-A, and B. cenocepacia III-B ribopatterns, respectively. These results demonstrated good FTIR spectroscopy discrimination capacity at the ribopattern level, for the HSM isolates but showed difficulty at the species level, especially when the reference strains were included. Remarkably, this methodology was found to discriminate isolates belonging to the same species and ribopattern that were collected from the same patient during prolonged colonization, opening the door to the identification of chemical modifications resulting from adaptation strategies to the CF lung stressing environment, in particular to aggressive and prolonged antibiotic therapy. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

星际媒介H2NCH2CN与H2O反应中的H2O分子偶合质子转移机理和氢隧道效应

H2NCH2CN+H2O→H2NCH2C(OH)NH是一个重要的反应, 涉及到星际媒介中甘氨酸的形成, 与早期地球上的氨基酸起源有关. 如果没有考虑氢隧道效应, 在MP2/6-311+G(d,p)级别上计算反应能垒是254.7 kJ·mol-1, 在星际媒介中该气相反应很难进行. 在星际媒介冰颗粒表面上, 水分子催化反应增强了该化学反应的活性. H2NCH2CN与(H2O)3反应中的两个水分子作为催化剂降低活化能77.5 kJ·mol-1和活化自由能70.9 kJ·mol-1, 并且通过氢键桥协同传递质子. 量子氢隧道对于该反应进行至关紧要,采用小弯曲隧道(SCT)近似和正则变分过渡态理论(CVT)方法研究. 温度50 K时, 速率常数kSCT/CVT为1.86×10-23 cm3·molecule-1·s-1, 表明在星际媒介中通过质子隧道机理该反应容易进行. 研究结果与地球上的氨基酸起源于地球本身物质的观点相一致.     

土壤重金属污染来源及其解析研究进展

土壤重金属污染问题是环境和土壤科学研究者关注的热点问题。对土壤重金属污染物来源的鉴别是准确、有效控制和治理污染源的前提。根据近年来国内外对土壤重金属污染的相关研究报道,综述了土壤中污染物的工业、农业和交通因子三大主要来源,重点阐述了目前解析土壤重金属污染来源所运用的化学形态研究、剖面分布、同位素示踪、空间分析和多元统计等方法,并就存在的问题和今后的研究重点进行了总结。     

原油饱和烃指纹的内标法分析

采用内标法建立了原油中正构烷烃、生物标志物(甾、萜烷类)的分析方法。确定了样品前处理方法和组分定性定量方法。讨论了柱层析分离能力。结果表明,所有饱和烃组分均流入第一部分流出液F1中,分离能力较为满意。对48种甾、萜烷类生物标志物组分以及姥鲛烷、植烷和正构烷烃等进行了定性确认,定性化合物数量多,信息量大,易于据此进行可靠的油指纹分析鉴别。32个正构烷烃组分相对标准差为1.2%～7.4%;45个生物标志物组分相对标准偏差为2.5%～9.2%。分析精密度较好,满足油指纹鉴别需要。正构烷烃回收率为73%～116%;生物标志物为84%～106%;回收率结果较为满意。正构烷烃方法检出限为7.0μg/g;生物标志物为0.65μg/g,满足原油样品分析要求。通过本方法对自不同和相同平台的原油样品进行饱和烃浓度分析,并采用浓度数据进行鉴别,结果与实际情况相符。     

Identification and determination of aminopeptidase activities secreted by lemon balm

Using synthetic substrates, an uncomplicated and sensitive procedure for the identification and determination of extracellular aminopeptidase was developed. The β-naphthylamides of the amino acids were applied for the identification of extracellular aminopeptidase, whereas the 4-(phenylazo) phenylamides of the amino acids were used for the determination of intra-and extracellular aminopeptidase activity. The results show a 81.8–88.9% intracellular and 11.1–18.2% extracellular distribution of the studied enzyme activity. Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 167–169, March–April, 2007.