气相色谱-质谱联用法测定野生和栽培宁前胡中挥发油成分

目的 采用气相色谱-质谱联用法（gas chromatography-mass spectrometry, GC-MS）分析不同生长条件下宁前胡中挥发油成分,研究野生和栽培宁前胡挥发油成分含量及种类的区别。方法 以安徽省宁国市中溪镇野生和栽培宁前胡、宁国市万家乡镇栽培宁前胡、宁国市栽培宁前胡（统货）为样品,采用《中华人民共和国药典》一部甲法提取挥发油,GC-MS分析挥发油化学成分,归一化法计算各组分的相对含量。结果 宁国市中溪镇野生宁前胡总挥发油含量为98.58%,栽培宁前胡总挥发油含量为93.48%;万家乡栽培宁前胡总挥发油含量为99.50%;宁国市栽培宁前胡（统货）总挥发油含量为95.89%。宁前胡挥发油中共鉴定出78个成分,烯烃类为主要化学成分,不同生长条件下宁前胡中烯烃类含量分别为野生宁前胡65.26%,中溪镇栽培宁前胡89.88%,万家乡栽培宁前胡62.08%,栽培宁前胡（统货）66.11%;所有烯烃类成分中,α-蒎烯的含量均最高。结论 野生和栽培宁前胡中挥发油成分差异较大,可以通过闻“气”辨别野生前胡与栽培前胡。     

衍生化-液相色谱-质谱联用测定血中氟乙酸类杀鼠剂

目的建立血中氟乙酸类杀鼠剂衍生化-液相色谱-电喷雾离子阱质谱分析方法。方法血样经乙腈沉淀蛋白后离心,上清液中加入衍生化试剂α-溴苯乙酮和催化剂四丁基溴化铵,在60℃水浴中加热90min,衍生化产物直接进行液相色谱-电喷雾离子阱质谱联用分析。结果血中氟乙酸根浓度在0.15μg/mL～15.40μg/mL之间具有良好的线性关系,最低检出限为0.020μg/mL。结论本文建立的方法操作简便、灵敏、快速,适用于刑事案件中氟乙酸类杀鼠剂的快速检验。     

Progress Toward the Determination of Correct Classification Rates in Fire Debris Analysis,,

Principal components analysis (PCA), linear discriminant analysis (LDA), and quadratic discriminant analysis (QDA) were used to develop a multistep classification procedure for determining the presence of ignitable liquid residue in fire debris and assigning any ignitable liquid residue present into the classes defined under the American Society for Testing and Materials (ASTM) E 1618‐10 standard method. A multistep classification procedure was tested by cross‐validation based on model data sets comprised of the time‐averaged mass spectra (also referred to as total ion spectra) of commercial ignitable liquids and pyrolysis products from common building materials and household furnishings (referred to simply as substrates). Fire debris samples from laboratory‐scale and field test burns were also used to test the model. The optimal model's true‐positive rate was 81.3% for cross‐validation samples and 70.9% for fire debris samples. The false‐positive rate was 9.9% for cross‐validation samples and 8.9% for fire debris samples.     

A novel method for the analysis of discharged smokeless powder residues

A novel method for the estimation of intermediate-long firing distance range is proposed. The method is based on the characterization and chemical analysis of the smokeless powder particles on the target. An adhesive lifter is applied to collect the suspected gunshot residues (GSRs) from the surface of an object, and a Modified Griess Test (MGT) is carried out after alkaline hydrolysis on the adhesive lifter. Visualized particles are removed from the adhesive lifter under a microscope. Two systems are used for the analysis of organic discharge residues from the smokeless powder: (1) gas chromatography/thermal energy analysis (GC/TEA) for the analysis of nitroglycerine (NG) and 2,4-dinitrotoluene (2,4-DNT), (2) gas chromatography/mass spectrometry (GC/MS) for the identification of organic components such as DNT, NG, and some stabilizers. By using this procedure and confirming that the suspected particles are indeed GSR, one can estimate the intermediate-long firing distance of c. 0.75-3 m in the presence of very few particles and provide information for the classification of ammunition type in casework.     

A detailed mechanistic fragmentation analysis of methamphetamine and select regioisomers by GC/MS

A novel ring-substituted methamphetamine regioisomer, N,alpha,4-trimethyl phenmethylamine, was synthesized in order to study the validity of proposed structures for various mass spectrometry (MS)-derived peaks in a methamphetamine fragmentation pattern. While other research efforts have studied aspects of methamphetamine in detail, a full fragmentation study has not been reported previously. In addition to showing molecular structures represented by fragment peaks, mechanisms for selected processes are detailed. An empirically derived procedure to easily determine by simple spectral peak pattern recognition the geometry of dimethyl- or ethyl-substituted immonium ions (RRC = N+ RR) where m/z = 58 is outlined. These results are platform independent for electron ionization (EI) instruments, but have also proven to be helpful in explaining spectral peaks observed in spectra from ion trap systems. The spectrum for the synthesized methamphetamine regioisomer was accurately predicted using this methodology. While this approach is useful in some casework, the converse may be more useful: when an unexpected or unusual peak pattern arises in a spectrum, being able to analyze it to determine the structure of the molecule. This paper gives an analyst the means to begin such retro-synthetic analyses.     

Contribution of thermal desorption and liquid-liquid extraction for identification and profiling of impurities in methamphetamine by gas chromatography-mass spectrometry

Impurity profiling of methamphetamine (MA) using thermal desorption (TD) and gas chromatography-mass spectrometry (GC-MS) was examined. Using TD/GC-MS, impurities were extracted and separated under various conditions. Optimal chromatograms were obtained when a 20 mg MA sample was extracted at 120 degrees C for 3 min using a TD instrument, followed by separation of the extracts using a non-polar capillary column coated with (5%phenyl)-methylpolysiloxane. MA samples from nine different batches were analyzed under optimized conditions. Compounds related to the structure of MA, such as benzaldehyde, benzyl alcohol, amphetamine, cis- and trans-1,2-dimethyl-3-phenylaziridine, dimethylamphetamine, and N-acetylephedrine, were detected in the chromatograms without any laborious extraction procedure. Compounds such as ethanol, diethyl ether, and acetic acid, which are considered reagents and solvents for MA synthesis, were also detected in some of the chromatograms. The numbers and intensities of the peaks detected were different among the samples. Impurity profiling of MA using TD was compared with that using liquid-liquid extraction (LLE). Better reproducibility of peak areas was obtained using LLE, whereas higher intensities and numbers of peaks were detected using TD. Solvents were extracted more effectively using TD. The nine batches of MA were classified using both extraction procedures. The nine batches were divided roughly into two groups using data from LLE. Subsequently, the groups were classified in detail using data from TD. TD can be used to provide supplemental information for LLE, and the combination of these extraction methods can be helpful for impurity profiling of MA.     

原子吸收光谱法测定中华芦荟微量元素

目的：测定中华芦荟中的微量元素.方法：用浓HNO3 10 ml和HClO4 2 ml（体积分数比为5[DK]∶1）作消化液处理样品,去离子水移取消化液并定容后采用原子吸收光谱法.结果：测定了样品中的Pb、Mn、Zn、K、Ca、Fe、Cd、Hg、As等9种微量元素,标准加样回收率为95.28%～105.4%.结论：该法简便、快速,为微量元素与芦荟药效之间的关系提供了可靠的依据.     

顶空气质联用法测定腐败血、肝检材中CO

目的研究CO中毒腐败血、肝组织检材中CO的HS/GC/MS检测。方法用HS/GC/MS法分析碳氧血红蛋白(COHb)血的线性范围。配制10%、30%、50%、70%浓度COHb血样,分别在室温、冷藏、冷冻条件下保存,分别在当日、第4、14、45d进行测定,比较实验结果。腐败肝组织由雄性健康家兔通CO气体致死,当天解剖,家兔肝常温隔绝空气保存并放35d至腐败,期间进行不定期顶空测定分析。结果制备的COHb血在0-100%之间有良好的线性关系Y=2.4X+2.2(r=0.9995)。以此方法测定家兔CO中毒致死的COHb新鲜血的浓度和4℃下放置45dCOHb腐败血,结果表明温度对血样中COHb%的测定影响最大。采用HS/GC/MS法检测,每次只需0.25ml血样或1g肝脏,分析一次时间只需3min,均可检测出新鲜检材和常温放置45d的腐败肝组织检材CO的含量。结论HS/GC/MS法能检出CO中毒的腐败生物检材中CO。     

CO<Subscript>2</Subscript> emission allowance allocation mechanisms,allocative efficiency and the environment: a static and dynamic perspective

The object of this paper is to place allocation mechanisms into a framework of Emission Trading Systems and thereby to establish a typology. It analyses how various assignment mechanisms deal with issues such as price determination, allocative efficiency and environmental considerations in a static and dynamic economy model. It analyses how allocation mechanisms are to be ranked and whether they serve the attainment of the general equilibrium. First the paper examines how market-based allocation mechanisms (auctions) perform in light of the above issues. Second the paper distinguishes between the two types of administrative allocation mechanisms: (1) financial administrative allocation mechanisms, combining payment schemes with bureaucratic expertise, and (2) free administrative allocation mechanisms, based inter alia on industrial policy considerations and on passed emission records (grandfathering). In particular, the value added of relative performance standards, which are for example included in the “Performance Standard Rate” (PSR) Emission Trading System, are examined as a means to provide allowances. The overall finding is that in a closed static economy and in the presence of an efficient trading market, different allocation methods produce equally efficient outcomes in allocative and environmental respects. With regard to an open dynamic economy, the impact of initial allocation mechanisms resembles those of a static closed economy. In such an economy the upper limit to the internalisation of negative externalities is given by operator’s costs of environmentally harmful relocation and hence the cost burden placed upon operators is crucial. Auctions and financial administrative allocation mechanisms perform less well than free administrative mechanisms. Relative standard base mechanisms, constituting an important element of the PSR Emission Trading System, perform better than grandfathering schemes because they take into account abatement possibilities of industries, minimise stranded costs and do not give rise to time shifting of abatement projects. It is therefore concluded that allocation mechanisms merit more attention than the discussion relating to capped trade and trade without a cap.      

Multiplex PCR electrospray-ionization mass spectrometry (ESI-MS): Application to forensic mitochondrial DNA examinations

Mitochondrial DNA (mtDNA) examinations play an important role in criminal investigations, identification of victims of mass disasters, and association of unidentified remains with family members. Typically, HV1 and HV2 are amplified via polymerase chain reaction (PCR) followed by fluorescent sequencing. While this method produces the highest level of resolution, it is labor intensive and unable to distinguish components of a mixture. Previously, an electrospray-ionization mass spectrometry (ESI-MS) method was described to determine the base composition profile of enzymatically digested PCR amplified fragments derived from the HV1 and HV2 regions. Advantages of ESI-MS compared to sequencing include speed of analysis, automation, and increased sensitivity, while retaining a high degree of resolution. Here, we report the next generation of this method in which a base composition profile is determined from 24 overlapping PCR reactions. Because ESI-MS provides the relative abundance of each component present, this method allows for the quantitative typing of mixtures. This ESI-MS method does not rely on a priori knowledge of variable sites, allowing the capture of private mutations and individual-specific variation. Due to the multiplex design, automation, speed of analysis, and ability to interrogate mixtures, this method provides a powerful and rapid tool for forensic mtDNA examinations.